diff --git a/app/Models/Concerns/AuditableThroughParent.php b/app/Models/Concerns/AuditableThroughParent.php
new file mode 100644
index 00000000..47856c7c
--- /dev/null
+++ b/app/Models/Concerns/AuditableThroughParent.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models\Concerns;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+/**
+ * Marks an auditable model whose audits are owned by the owner of its parent model,
+ * because the model itself has no organization_id (for example a project member belongs to an organization via its project).
+ * The parent model has to have an organization_id column.
+ * This is used to set the owner of new audits (CustomAuditable) and to backfill the owner of existing audits.
+ */
+interface AuditableThroughParent
+{
+    /**
+     * @return BelongsTo<covariant Model, covariant Model>
+     */
+    public function getAuditParentRelation(): BelongsTo;
+}
diff --git a/app/Models/Concerns/CustomAuditable.php b/app/Models/Concerns/CustomAuditable.php
index 150bfb21..1557c0c0 100644
--- a/app/Models/Concerns/CustomAuditable.php
+++ b/app/Models/Concerns/CustomAuditable.php
@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace App\Models\Concerns;
 
+use Illuminate\Database\Eloquent\Model;
 use Illuminate\Support\Facades\Config;
 use OwenIt\Auditing\Auditable;
 
@@ -27,6 +28,36 @@ trait CustomAuditable
      */
     public function getAuditOwnerOrganizationId(): ?string
     {
+        if ($this instanceof AuditableThroughParent) {
+            $relation = $this->getAuditParentRelation();
+            $parentId = $this->getAttributes()[$relation->getForeignKeyName()] ?? null;
+            if ($parentId === null) {
+                return null;
+            }
+
+            // Note: The loaded parent is only used if it still matches the foreign key and was loaded with the organization
+            $relationName = $relation->getRelationName();
+            if ($this->relationLoaded($relationName)) {
+                $parent = $this->getRelation($relationName);
+                if ($parent instanceof Model
+                    && $parent->getAttribute($relation->getOwnerKeyName()) === $parentId
+                    && array_key_exists('organization_id', $parent->getAttributes())) {
+                    /** @var string|null $organizationId */
+                    $organizationId = $parent->getAttributes()['organization_id'];
+
+                    return $organizationId;
+                }
+            }
+
+            /** @var string|null $organizationId */
+            $organizationId = $relation->getRelated()->newQuery()
+                ->toBase()
+                ->where($relation->getOwnerKeyName(), $parentId)
+                ->value('organization_id');
+
+            return $organizationId;
+        }
+
         return $this->getAttributes()['organization_id'] ?? null;
     }
 
diff --git a/app/Models/ProjectMember.php b/app/Models/ProjectMember.php
index 5d45095d..1bff0042 100644
--- a/app/Models/ProjectMember.php
+++ b/app/Models/ProjectMember.php
@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace App\Models;
 
+use App\Models\Concerns\AuditableThroughParent;
 use App\Models\Concerns\CustomAuditable;
 use App\Models\Concerns\HasUuids;
 use Database\Factories\ProjectMemberFactory;
@@ -29,7 +30,7 @@ use OwenIt\Auditing\Contracts\Auditable as AuditableContract;
  * @method static Builder<ProjectMember> whereBelongsToOrganization(Organization $organization)
  * @method static ProjectMemberFactory factory()
  */
-class ProjectMember extends Model implements AuditableContract
+class ProjectMember extends Model implements AuditableContract, AuditableThroughParent
 {
     use CustomAuditable;
 
@@ -83,11 +84,11 @@ class ProjectMember extends Model implements AuditableContract
         });
     }
 
-    public function getAuditOwnerOrganizationId(): ?string
+    /**
+     * @return BelongsTo<Project, $this>
+     */
+    public function getAuditParentRelation(): BelongsTo
     {
-        /** @var string|null $organizationId */
-        $organizationId = Project::query()->whereKey($this->project_id)->value('organization_id');
-
-        return $organizationId;
+        return $this->project();
     }
 }
diff --git a/tests/Unit/Model/AuditModelTest.php b/tests/Unit/Model/AuditModelTest.php
index 6e0950a9..f08daa85 100644
--- a/tests/Unit/Model/AuditModelTest.php
+++ b/tests/Unit/Model/AuditModelTest.php
@@ -14,6 +14,7 @@ use App\Models\TimeEntry;
 use App\Models\User;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\Relation;
+use Illuminate\Support\Facades\DB;
 use PHPUnit\Framework\Attributes\CoversClass;
 
 #[CoversClass(Audit::class)]
@@ -84,6 +85,41 @@ class AuditModelTest extends ModelTestAbstract
         $this->assertNull($audit->owner_user_id);
     }
 
+    public function test_owner_organization_through_parent_uses_the_loaded_parent_without_query(): void
+    {
+        // Arrange
+        $organization = Organization::factory()->create();
+        $project = Project::factory()->forOrganization($organization)->create();
+        $projectMember = ProjectMember::factory()->forProject($project)->forMember(Member::factory()->forOrganization($organization)->create())->create();
+        $projectMember->load('project');
+        DB::enableQueryLog();
+
+        // Act
+        $ownerOrganizationId = $projectMember->getAuditOwnerOrganizationId();
+
+        // Assert
+        $this->assertSame($organization->getKey(), $ownerOrganizationId);
+        $this->assertCount(0, DB::getQueryLog());
+    }
+
+    public function test_owner_organization_through_parent_ignores_a_loaded_parent_that_does_not_match_the_foreign_key(): void
+    {
+        // Arrange
+        $organization = Organization::factory()->create();
+        $otherOrganization = Organization::factory()->create();
+        $project = Project::factory()->forOrganization($organization)->create();
+        $otherProject = Project::factory()->forOrganization($otherOrganization)->create();
+        $projectMember = ProjectMember::factory()->forProject($project)->forMember(Member::factory()->forOrganization($organization)->create())->create();
+        $projectMember->load('project');
+        $projectMember->project_id = $otherProject->getKey();
+
+        // Act
+        $ownerOrganizationId = $projectMember->getAuditOwnerOrganizationId();
+
+        // Assert
+        $this->assertSame($otherOrganization->getKey(), $ownerOrganizationId);
+    }
+
     public function test_audits_of_an_organization_have_the_organization_itself_as_owner(): void
     {
         // Act