diff --git a/app/Console/Commands/Correction/CorrectionPlaceholderMembersCommand.php b/app/Console/Commands/Correction/CorrectionPlaceholderMembersCommand.php
new file mode 100644
index 00000000..2f666fd4
--- /dev/null
+++ b/app/Console/Commands/Correction/CorrectionPlaceholderMembersCommand.php
@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Console\Commands\Correction;
+
+use App\Enums\Role;
+use App\Models\Member;
+use App\Models\User;
+use Illuminate\Console\Command;
+use Illuminate\Database\Eloquent\Builder;
+
+class CorrectionPlaceholderMembersCommand extends Command
+{
+    /**
+     * The name and signature of the console command.
+     *
+     * @var string
+     */
+    protected $signature = 'correction:placeholder-members '.
+        ' { --dry-run : Do not actually save anything to the database, just output what would happen }';
+
+    /**
+     * The console command description.
+     *
+     * @var string
+     */
+    protected $description = 'Sets all members who belong to a placeholder user to role placeholder';
+
+    /**
+     * Execute the console command.
+     */
+    public function handle(): int
+    {
+        $this->comment('Sets all members who belong to a placeholder user to role placeholder...');
+        $dryRun = (bool) $this->option('dry-run');
+        if ($dryRun) {
+            $this->comment('Running in dry-run mode. Nothing will be saved to the database.');
+        }
+
+        $members = Member::query()
+            ->where('role', '!=', Role::Placeholder->value)
+            ->whereHas('user', function (Builder $builder): void {
+                /** @var Builder<User> $builder */
+                $builder->where('is_placeholder', '=', true);
+            })
+            ->get();
+        foreach ($members as $member) {
+            /** @var Member $member */
+            $member->role = Role::Placeholder->value;
+            if (! $dryRun) {
+                $member->save();
+            }
+            $this->line('Set role of member (id='.$member->getKey().') to placeholder');
+        }
+
+        return self::SUCCESS;
+    }
+}
diff --git a/app/Exceptions/Api/ChangingRoleOfPlaceholderIsNotAllowed.php b/app/Exceptions/Api/ChangingRoleOfPlaceholderIsNotAllowed.php
new file mode 100644
index 00000000..4f18c5a9
--- /dev/null
+++ b/app/Exceptions/Api/ChangingRoleOfPlaceholderIsNotAllowed.php
@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Exceptions\Api;
+
+class ChangingRoleOfPlaceholderIsNotAllowed extends ApiException
+{
+    public const string KEY = 'changing_role_of_placeholder_is_not_allowed';
+}
diff --git a/app/Exceptions/Api/OnlyPlaceholdersCanBeMergedIntoAnotherMember.php b/app/Exceptions/Api/OnlyPlaceholdersCanBeMergedIntoAnotherMember.php
new file mode 100644
index 00000000..9f14c975
--- /dev/null
+++ b/app/Exceptions/Api/OnlyPlaceholdersCanBeMergedIntoAnotherMember.php
@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Exceptions\Api;
+
+class OnlyPlaceholdersCanBeMergedIntoAnotherMember extends ApiException
+{
+    public const string KEY = 'only_placeholders_can_be_merged_into_another_member';
+}
diff --git a/app/Exceptions/Api/ThisPlaceholderCanNotBeInvitedUseTheMergeToolInsteadException.php b/app/Exceptions/Api/ThisPlaceholderCanNotBeInvitedUseTheMergeToolInsteadException.php
new file mode 100644
index 00000000..b2d13790
--- /dev/null
+++ b/app/Exceptions/Api/ThisPlaceholderCanNotBeInvitedUseTheMergeToolInsteadException.php
@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Exceptions\Api;
+
+class ThisPlaceholderCanNotBeInvitedUseTheMergeToolInsteadException extends ApiException
+{
+    public const string KEY = 'this_placeholder_can_not_be_invited_use_the_merge_tool_instead_api_exception';
+}
diff --git a/app/Http/Controllers/Api/V1/MemberController.php b/app/Http/Controllers/Api/V1/MemberController.php
index c1e1220f..8e3a82fd 100644
--- a/app/Http/Controllers/Api/V1/MemberController.php
+++ b/app/Http/Controllers/Api/V1/MemberController.php
@@ -7,12 +7,17 @@ namespace App\Http\Controllers\Api\V1;
 use App\Enums\Role;
 use App\Events\MemberMadeToPlaceholder;
 use App\Exceptions\Api\CanNotRemoveOwnerFromOrganization;
+use App\Exceptions\Api\ChangingRoleOfPlaceholderIsNotAllowed;
 use App\Exceptions\Api\ChangingRoleToPlaceholderIsNotAllowed;
 use App\Exceptions\Api\EntityStillInUseApiException;
 use App\Exceptions\Api\OnlyOwnerCanChangeOwnership;
+use App\Exceptions\Api\OnlyPlaceholdersCanBeMergedIntoAnotherMember;
 use App\Exceptions\Api\OrganizationNeedsAtLeastOneOwner;
+use App\Exceptions\Api\ThisPlaceholderCanNotBeInvitedUseTheMergeToolInsteadException;
+use App\Exceptions\Api\UserIsAlreadyMemberOfOrganizationApiException;
 use App\Exceptions\Api\UserNotPlaceholderApiException;
 use App\Http\Requests\V1\Member\MemberIndexRequest;
+use App\Http\Requests\V1\Member\MemberMergeIntoRequest;
 use App\Http\Requests\V1\Member\MemberUpdateRequest;
 use App\Http\Resources\V1\Member\MemberCollection;
 use App\Http\Resources\V1\Member\MemberResource;
@@ -21,9 +26,12 @@ use App\Models\Organization;
 use App\Service\BillableRateService;
 use App\Service\InvitationService;
 use App\Service\MemberService;
+use App\Service\UserService;
 use Illuminate\Auth\Access\AuthorizationException;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Http\Resources\Json\JsonResource;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Str;
 
 class MemberController extends Controller
 {
@@ -63,6 +71,7 @@ class MemberController extends Controller
      * @throws OrganizationNeedsAtLeastOneOwner
      * @throws OnlyOwnerCanChangeOwnership
      * @throws ChangingRoleToPlaceholderIsNotAllowed
+     * @throws ChangingRoleOfPlaceholderIsNotAllowed
      *
      * @operationId updateMember
      */
@@ -105,7 +114,7 @@ class MemberController extends Controller
     /**
      * Make a member a placeholder member
      *
-     * @throws AuthorizationException|CanNotRemoveOwnerFromOrganization
+     * @throws AuthorizationException|CanNotRemoveOwnerFromOrganization|ChangingRoleOfPlaceholderIsNotAllowed
      */
     public function makePlaceholder(Organization $organization, Member $member, MemberService $memberService): JsonResponse
     {
@@ -114,6 +123,9 @@ class MemberController extends Controller
         if ($member->role === Role::Owner->value) {
             throw new CanNotRemoveOwnerFromOrganization;
         }
+        if ($member->role === Role::Placeholder->value) {
+            throw new ChangingRoleOfPlaceholderIsNotAllowed;
+        }
 
         $memberService->makeMemberToPlaceholder($member);
 
@@ -122,10 +134,37 @@ class MemberController extends Controller
         return response()->json(null, 204);
     }
 
+    /**
+     * @throws AuthorizationException
+     * @throws OnlyPlaceholdersCanBeMergedIntoAnotherMember
+     * @throws \Throwable
+     */
+    public function mergeInto(Organization $organization, Member $member, MemberMergeIntoRequest $request): JsonResponse
+    {
+        $this->checkPermission($organization, 'members:merge-into', $member);
+
+        $user = $member->user;
+        if ($member->role !== Role::Placeholder->value || ! $user->is_placeholder) {
+            throw new OnlyPlaceholdersCanBeMergedIntoAnotherMember;
+        }
+        $memberTo = Member::findOrFail($request->getMemberId());
+
+        DB::transaction(function () use ($organization, $member, $user, $memberTo): void {
+            app(UserService::class)->assignOrganizationEntitiesToDifferentMember($organization, $user, $memberTo->user, $memberTo);
+            $member->delete();
+            $user->delete();
+        });
+
+        return response()->json(null, 204);
+    }
+
     /**
      * Invite a placeholder member to become a real member of the organization
      *
-     * @throws AuthorizationException|UserNotPlaceholderApiException
+     * @throws AuthorizationException
+     * @throws UserNotPlaceholderApiException
+     * @throws UserIsAlreadyMemberOfOrganizationApiException
+     * @throws ThisPlaceholderCanNotBeInvitedUseTheMergeToolInsteadException
      *
      * @operationId invitePlaceholder
      */
@@ -138,6 +177,10 @@ class MemberController extends Controller
             throw new UserNotPlaceholderApiException;
         }
 
+        if (Str::endsWith($user->email, '@solidtime-import.test')) {
+            throw new ThisPlaceholderCanNotBeInvitedUseTheMergeToolInsteadException;
+        }
+
         $invitationService->inviteUser($organization, $user->email, Role::Employee);
 
         return response()->json(null, 204);
diff --git a/app/Http/Requests/V1/Member/MemberMergeIntoRequest.php b/app/Http/Requests/V1/Member/MemberMergeIntoRequest.php
new file mode 100644
index 00000000..b341811a
--- /dev/null
+++ b/app/Http/Requests/V1/Member/MemberMergeIntoRequest.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Requests\V1\Member;
+
+use App\Models\Member;
+use App\Models\Organization;
+use Illuminate\Contracts\Validation\ValidationRule;
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Foundation\Http\FormRequest;
+use Korridor\LaravelModelValidationRules\Rules\ExistsEloquent;
+
+/**
+ * @property Organization $organization
+ */
+class MemberMergeIntoRequest extends FormRequest
+{
+    /**
+     * Get the validation rules that apply to the request.
+     *
+     * @return array<string, array<string|ValidationRule|\Illuminate\Contracts\Validation\Rule>>
+     */
+    public function rules(): array
+    {
+        return [
+            // ID of the member to which the data should be transferred (destination)
+            'member_id' => [
+                'string',
+                ExistsEloquent::make(Member::class, null, function (Builder $builder): Builder {
+                    /** @var Builder<Member> $builder */
+                    return $builder->whereBelongsTo($this->organization, 'organization');
+                })->uuid(),
+            ],
+        ];
+    }
+
+    public function getMemberId(): string
+    {
+        return (string) $this->input('member_id');
+    }
+}
diff --git a/app/Models/Member.php b/app/Models/Member.php
index 2c9fba3c..694ec26e 100644
--- a/app/Models/Member.php
+++ b/app/Models/Member.php
@@ -7,6 +7,7 @@ namespace App\Models;
 use App\Models\Concerns\CustomAuditable;
 use App\Models\Concerns\HasUuids;
 use Database\Factories\MemberFactory;
+use Illuminate\Database\Eloquent\Collection;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\Relations\HasMany;
@@ -24,6 +25,8 @@ use OwenIt\Auditing\Contracts\Auditable as AuditableContract;
  * @property Carbon|null $updated_at
  * @property-read Organization $organization
  * @property-read User $user
+ * @property-read Collection<ProjectMember> $projectMembers
+ * @property-read Collection<TimeEntry> $timeEntries
  *
  * @method static MemberFactory factory()
  */
@@ -59,6 +62,14 @@ class Member extends JetstreamMembership implements AuditableContract
         return $this->belongsTo(Organization::class, 'organization_id');
     }
 
+    /**
+     * @return HasMany<TimeEntry>
+     */
+    public function timeEntries(): HasMany
+    {
+        return $this->hasMany(TimeEntry::class, 'member_id');
+    }
+
     /**
      * @return HasMany<ProjectMember>
      */
diff --git a/app/Service/MemberService.php b/app/Service/MemberService.php
index b5c1f6e0..c5645595 100644
--- a/app/Service/MemberService.php
+++ b/app/Service/MemberService.php
@@ -7,6 +7,7 @@ namespace App\Service;
 use App\Enums\Role;
 use App\Events\MemberRemoved;
 use App\Exceptions\Api\CanNotRemoveOwnerFromOrganization;
+use App\Exceptions\Api\ChangingRoleOfPlaceholderIsNotAllowed;
 use App\Exceptions\Api\ChangingRoleToPlaceholderIsNotAllowed;
 use App\Exceptions\Api\EntityStillInUseApiException;
 use App\Exceptions\Api\OnlyOwnerCanChangeOwnership;
@@ -75,6 +76,7 @@ class MemberService
      * @throws ChangingRoleToPlaceholderIsNotAllowed
      * @throws OnlyOwnerCanChangeOwnership
      * @throws OrganizationNeedsAtLeastOneOwner
+     * @throws ChangingRoleOfPlaceholderIsNotAllowed
      */
     public function changeRole(Member $member, Organization $organization, Role $newRole, bool $allowOwnerChange): void
     {
@@ -82,6 +84,9 @@ class MemberService
         if ($oldRole === Role::Owner) {
             throw new OrganizationNeedsAtLeastOneOwner;
         }
+        if ($oldRole === Role::Placeholder) {
+            throw new ChangingRoleOfPlaceholderIsNotAllowed;
+        }
         if ($newRole === Role::Placeholder) {
             throw new ChangingRoleToPlaceholderIsNotAllowed;
         }
diff --git a/lang/en/exceptions.php b/lang/en/exceptions.php
index a69e2848..832a9898 100644
--- a/lang/en/exceptions.php
+++ b/lang/en/exceptions.php
@@ -4,15 +4,18 @@ declare(strict_types=1);
 
 use App\Exceptions\Api\CanNotDeleteUserWhoIsOwnerOfOrganizationWithMultipleMembers;
 use App\Exceptions\Api\CanNotRemoveOwnerFromOrganization;
+use App\Exceptions\Api\ChangingRoleOfPlaceholderIsNotAllowed;
 use App\Exceptions\Api\ChangingRoleToPlaceholderIsNotAllowed;
 use App\Exceptions\Api\EntityStillInUseApiException;
 use App\Exceptions\Api\FeatureIsNotAvailableInFreePlanApiException;
 use App\Exceptions\Api\InactiveUserCanNotBeUsedApiException;
 use App\Exceptions\Api\OnlyOwnerCanChangeOwnership;
+use App\Exceptions\Api\OnlyPlaceholdersCanBeMergedIntoAnotherMember;
 use App\Exceptions\Api\OrganizationHasNoSubscriptionButMultipleMembersException;
 use App\Exceptions\Api\OrganizationNeedsAtLeastOneOwner;
 use App\Exceptions\Api\PdfRendererIsNotConfiguredException;
 use App\Exceptions\Api\PersonalAccessClientIsNotConfiguredException;
+use App\Exceptions\Api\ThisPlaceholderCanNotBeInvitedUseTheMergeToolInsteadException;
 use App\Exceptions\Api\TimeEntryCanNotBeRestartedApiException;
 use App\Exceptions\Api\TimeEntryStillRunningApiException;
 use App\Exceptions\Api\UserIsAlreadyMemberOfOrganizationApiException;
@@ -39,6 +42,9 @@ return [
         PdfRendererIsNotConfiguredException::KEY => 'PDF renderer is not configured',
         FeatureIsNotAvailableInFreePlanApiException::KEY => 'Feature is not available in free plan',
         PersonalAccessClientIsNotConfiguredException::KEY => 'Personal access client is not configured',
+        ChangingRoleOfPlaceholderIsNotAllowed::KEY => 'Changing role of placeholder is not allowed',
+        OnlyPlaceholdersCanBeMergedIntoAnotherMember::KEY => 'Only placeholders can be merged into another member',
+        ThisPlaceholderCanNotBeInvitedUseTheMergeToolInsteadException::KEY => 'This placeholder can not be invited use the merge tool instead',
     ],
     'unknown_error_in_admin_panel' => 'An unknown error occurred. Please check the logs.',
 ];
diff --git a/lang/en/importer.php b/lang/en/importer.php
index 2c6cec3d..7d5f13a8 100644
--- a/lang/en/importer.php
+++ b/lang/en/importer.php
@@ -13,7 +13,7 @@ return [
             '<br> 4. Now click Export -> Save as CSV. The Export dropdown is in the header of the export table left of the printer symbol. '.
             '<br><br>Before you import make sure that the Timezone settings in Clockify are the same as in solidtime.',
     ],
-    'generic_project' => [
+    'generic_projects' => [
         'name' => 'Generic Projects',
         'description' => 'If you want to import many projects yourself this importer the right choice. Please see our docs for <a href="https://docs.solidtime.io/user-guide/import">more information about the CSV structure</a>',
     ],
diff --git a/routes/api.php b/routes/api.php
index ac3fc5c3..1c38f348 100644
--- a/routes/api.php
+++ b/routes/api.php
@@ -51,6 +51,7 @@ Route::prefix('v1')->name('v1.')->group(static function (): void {
             Route::delete('/members/{member}', [MemberController::class, 'destroy'])->name('destroy');
             Route::post('/members/{member}/invite-placeholder', [MemberController::class, 'invitePlaceholder'])->name('invite-placeholder');
             Route::post('/members/{member}/make-placeholder', [MemberController::class, 'makePlaceholder'])->name('make-placeholder');
+            Route::post('member/{member}/merge-into', [MemberController::class, 'mergeInto'])->name('merge-into');
         });
 
         // User routes
diff --git a/tests/Unit/Console/Commands/Correction/CorrectionPlaceholderMembersCommandTest.php b/tests/Unit/Console/Commands/Correction/CorrectionPlaceholderMembersCommandTest.php
new file mode 100644
index 00000000..651f1fb4
--- /dev/null
+++ b/tests/Unit/Console/Commands/Correction/CorrectionPlaceholderMembersCommandTest.php
@@ -0,0 +1,68 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Unit\Console\Commands\Correction;
+
+use App\Console\Commands\Correction\CorrectionPlaceholderMembersCommand;
+use App\Enums\Role;
+use App\Models\Member;
+use App\Models\Organization;
+use App\Models\User;
+use Illuminate\Console\Command;
+use Illuminate\Support\Facades\Artisan;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\UsesClass;
+use Tests\TestCaseWithDatabase;
+
+#[CoversClass(CorrectionPlaceholderMembersCommand::class)]
+#[UsesClass(CorrectionPlaceholderMembersCommand::class)]
+class CorrectionPlaceholderMembersCommandTest extends TestCaseWithDatabase
+{
+    public function test_sets_member_role_to_placeholder_if_user_is_placeholder(): void
+    {
+        // Arrange
+        $organization = Organization::factory()->create();
+        $user1 = User::factory()->placeholder()->create();
+        $member1 = Member::factory()->forOrganization($organization)->forUser($user1)->role(Role::Admin)->create();
+        $user2 = User::factory()->create();
+        $member2 = Member::factory()->forOrganization($organization)->forUser($user2)->role(Role::Admin)->create();
+
+        // Act
+        $exitCode = $this->withoutMockingConsoleOutput()->artisan('correction:placeholder-members');
+
+        // Assert
+        $this->assertSame(Command::SUCCESS, $exitCode);
+        $output = Artisan::output();
+        $member1->refresh();
+        $this->assertSame(Role::Placeholder->value, $member1->role);
+        $member2->refresh();
+        $this->assertSame(Role::Admin->value, $member2->role);
+        $this->assertSame("Sets all members who belong to a placeholder user to role placeholder...\n".
+            'Set role of member (id='.$member1->getKey().") to placeholder\n", $output);
+    }
+
+    public function test_sets_member_role_to_placeholder_if_user_is_placeholder_dry_run(): void
+    {
+        // Arrange
+        $organization = Organization::factory()->create();
+        $user1 = User::factory()->placeholder()->create();
+        $member1 = Member::factory()->forOrganization($organization)->forUser($user1)->role(Role::Admin)->create();
+        $user2 = User::factory()->create();
+        $member2 = Member::factory()->forOrganization($organization)->forUser($user2)->role(Role::Admin)->create();
+
+        // Act
+        $exitCode = $this->withoutMockingConsoleOutput()->artisan('correction:placeholder-members --dry-run');
+
+        // Assert
+        $this->assertSame(Command::SUCCESS, $exitCode);
+        $output = Artisan::output();
+        $member1->refresh();
+        $this->assertSame(Role::Admin->value, $member1->role);
+        $member2->refresh();
+        $this->assertSame(Role::Admin->value, $member2->role);
+        $this->assertSame("Sets all members who belong to a placeholder user to role placeholder...\n".
+            "Running in dry-run mode. Nothing will be saved to the database.\n".
+            'Set role of member (id='.$member1->getKey().") to placeholder\n", $output);
+    }
+}
diff --git a/tests/Unit/Endpoint/Api/V1/MemberEndpointTest.php b/tests/Unit/Endpoint/Api/V1/MemberEndpointTest.php
index 8f826117..6dfb3982 100644
--- a/tests/Unit/Endpoint/Api/V1/MemberEndpointTest.php
+++ b/tests/Unit/Endpoint/Api/V1/MemberEndpointTest.php
@@ -194,6 +194,164 @@ class MemberEndpointTest extends ApiEndpointTestAbstract
         $response->assertJsonPath('message', 'Only owner can change ownership');
     }
 
+    public function test_update_member_fails_if_user_tries_to_change_the_role_of_a_placeholder(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'members:update',
+        ]);
+        $user = User::factory()->placeholder()->create();
+        $member = Member::factory()->forOrganization($data->organization)->forUser($user)->role(Role::Placeholder)->create();
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->putJson(route('api.v1.members.update', [$data->organization->getKey(), $member->getKey()]), [
+            'role' => Role::Admin->value,
+        ]);
+
+        // Assert
+        $response->assertStatus(400);
+        $response->assertExactJson([
+            'error' => true,
+            'key' => 'changing_role_of_placeholder_is_not_allowed',
+            'message' => 'Changing role of placeholder is not allowed',
+        ]);
+    }
+
+    public function test_merge_into_fails_if_url_member_is_not_part_of_organization(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'members:merge-into',
+        ]);
+        $userSource = User::factory()->placeholder()->create();
+        $memberSource = Member::factory()->forUser($userSource)->role(Role::Placeholder)->create();
+
+        $userDestination = User::factory()->create();
+        $memberDestination = Member::factory()->forUser($userDestination)->forOrganization($data->organization)->role(Role::Admin)->create();
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->postJson(route('api.v1.members.merge-into', [$data->organization->getKey(), $memberSource->getKey()]), [
+            'member_id' => $memberDestination->getKey(),
+        ]);
+
+        // Assert
+        $response->assertForbidden();
+    }
+
+    public function test_merge_into_returns_validation_error_if_member_in_body_does_not_belong_to_organization(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'members:merge-into',
+        ]);
+        $userSource = User::factory()->placeholder()->create();
+        $memberSource = Member::factory()->forUser($userSource)->forOrganization($data->organization)->role(Role::Placeholder)->create();
+
+        $userDestination = User::factory()->create();
+        $memberDestination = Member::factory()->forUser($userDestination)->role(Role::Admin)->create();
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->postJson(route('api.v1.members.merge-into', [$data->organization->getKey(), $memberSource->getKey()]), [
+            'member_id' => $memberDestination->getKey(),
+        ]);
+
+        // Assert
+        $response->assertStatus(422);
+        $response->assertExactJson([
+            'errors' => [
+                'member_id' => [
+                    'The resource does not exist.',
+                ],
+            ],
+            'message' => 'The resource does not exist.',
+        ]);
+    }
+
+    public function test_merge_into_fails_if_from_member_is_not_a_placeholder(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'members:merge-into',
+        ]);
+        $userSource = User::factory()->placeholder()->create();
+        $memberSource = Member::factory()->forUser($userSource)->forOrganization($data->organization)->role(Role::Admin)->create();
+
+        $userDestination = User::factory()->create();
+        $memberDestination = Member::factory()->forUser($userDestination)->forOrganization($data->organization)->role(Role::Admin)->create();
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->postJson(route('api.v1.members.merge-into', [$data->organization->getKey(), $memberSource->getKey()]), [
+            'member_id' => $memberDestination->getKey(),
+        ]);
+
+        // Assert
+        $response->assertStatus(400);
+        $response->assertExactJson([
+            'error' => true,
+            'key' => 'only_placeholders_can_be_merged_into_another_member',
+            'message' => 'Only placeholders can be merged into another member',
+        ]);
+    }
+
+    public function test_merge_into_fails_if_user_has_no_permission_to_merge_members(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([]);
+        $userSource = User::factory()->placeholder()->create();
+        $memberSource = Member::factory()->forUser($userSource)->forOrganization($data->organization)->role(Role::Placeholder)->create();
+
+        $userDestination = User::factory()->create();
+        $memberDestination = Member::factory()->forUser($userDestination)->forOrganization($data->organization)->role(Role::Admin)->create();
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->postJson(route('api.v1.members.merge-into', [$data->organization->getKey(), $memberSource->getKey()]), [
+            'member_id' => $memberDestination->getKey(),
+        ]);
+
+        // Assert
+        $response->assertForbidden();
+    }
+
+    public function test_merge_into_assigns_resources_of_source_member_to_destination_member_and_deletes_member(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'members:merge-into',
+        ]);
+        $userSource = User::factory()->placeholder()->create();
+        $memberSource = Member::factory()->forUser($userSource)->forOrganization($data->organization)->role(Role::Placeholder)->create();
+        TimeEntry::factory()->forMember($memberSource)->createMany(3);
+        $project = Project::factory()->forOrganization($data->organization)->create();
+        ProjectMember::factory()->forMember($memberSource)->forProject($project)->create();
+
+        $userDestination = User::factory()->create();
+        $memberDestination = Member::factory()->forUser($userDestination)->forOrganization($data->organization)->role(Role::Admin)->create();
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->postJson(route('api.v1.members.merge-into', [$data->organization->getKey(), $memberSource->getKey()]), [
+            'member_id' => $memberDestination->getKey(),
+        ]);
+
+        // Assert
+        $response->assertStatus(204);
+        $this->assertSame('', $response->getContent());
+        $this->assertDatabaseMissing(Member::class, [
+            'id' => $memberSource->getKey(),
+        ]);
+        $this->assertDatabaseMissing(User::class, [
+            'id' => $userSource->getKey(),
+        ]);
+        $memberDestination->refresh();
+        $this->assertCount(3, $memberDestination->timeEntries);
+        $this->assertCount(1, $memberDestination->projectMembers);
+    }
+
     public function test_update_member_fails_if_user_tries_to_change_role_of_the_current_owner(): void
     {
         // Arrange
@@ -281,6 +439,7 @@ class MemberEndpointTest extends ApiEndpointTestAbstract
 
     public function test_invite_placeholder_succeeds_if_data_is_valid(): void
     {
+        // Arrange
         $data = $this->createUserWithPermission([
             'members:invite-placeholder',
         ]);
@@ -301,6 +460,38 @@ class MemberEndpointTest extends ApiEndpointTestAbstract
         $response->assertStatus(204);
     }
 
+    public function test_invite_placeholder_fails_if_the_placeholder_has_a_invalid_email_from_an_import(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'members:invite-placeholder',
+        ]);
+        $user = User::factory()->create([
+            'is_placeholder' => true,
+            'email' => 'some.user@solidtime-import.test',
+        ]);
+        $member = Member::factory()
+            ->forUser($user)
+            ->forOrganization($data->organization)
+            ->role(Role::Placeholder)
+            ->create();
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->postJson(route('api.v1.members.invite-placeholder', [
+            'organization' => $data->organization->getKey(),
+            'member' => $member->getKey(),
+        ]));
+
+        // Assert
+        $response->assertStatus(400);
+        $response->assertExactJson([
+            'error' => true,
+            'key' => 'this_placeholder_can_not_be_invited_use_the_merge_tool_instead_api_exception',
+            'message' => 'This placeholder can not be invited use the merge tool instead',
+        ]);
+    }
+
     public function test_destroy_member_fails_if_user_has_no_permission_to_delete_members(): void
     {
         // Arrange
@@ -455,6 +646,34 @@ class MemberEndpointTest extends ApiEndpointTestAbstract
         Event::assertNotDispatched(MemberMadeToPlaceholder::class);
     }
 
+    public function test_make_placeholder_fails_if_user_is_already_a_placeholder(): void
+    {
+        // Arrange
+        Event::fake([
+            MemberMadeToPlaceholder::class,
+        ]);
+        $data = $this->createUserWithPermission([
+            'members:make-placeholder',
+        ]);
+        $user = User::factory()->placeholder()->create();
+        $member = Member::factory()->forUser($user)->forOrganization($data->organization)->role(Role::Placeholder)->create();
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->postJson(route('api.v1.members.make-placeholder', [
+            'organization' => $data->organization->getKey(),
+            'member' => $member->getKey(),
+        ]));
+
+        // Assert
+        $response->assertStatus(400);
+        $response->assertExactJson([
+            'error' => true,
+            'key' => 'changing_role_of_placeholder_is_not_allowed',
+            'message' => 'Changing role of placeholder is not allowed',
+        ]);
+    }
+
     public function test_make_placeholder_fails_if_member_is_owner(): void
     {
         // Arrange