diff --git a/application/src/Domain/SourceManagement/SourceMemberManager.php b/application/src/Domain/SourceManagement/SourceMemberManager.php
new file mode 100644
index 0000000..36dcd63
--- /dev/null
+++ b/application/src/Domain/SourceManagement/SourceMemberManager.php
@@ -0,0 +1,50 @@
+<?php
+
+namespace App\Domain\SourceManagement;
+
+use App\Entity\Source\SourceInterface;
+
+final class SourceMemberManager implements SourceMemberManagerInterface
+{
+    /**
+     * @var SourceInterface
+     */
+    private $source;
+
+    public function __construct(SourceInterface $source)
+    {
+        $this->source = $source;
+    }
+
+    public function addMember(SourceInterface $member): void
+    {
+        if (!$this->source->getMembers()->contains($member)) {
+            $this->source->getMembers()[] = $member;
+            (new self($member))->addMembership($this->source);
+        }
+    }
+
+    public function removeMember(SourceInterface $member): void
+    {
+        if ($this->source->getMembers()->contains($member)) {
+            $this->source->getMembers()->removeElement($member);
+            (new self($member))->removeMembership($this->source);
+        }
+    }
+
+    public function addMembership(SourceInterface $membership): void
+    {
+        if (!$this->source->getMemberships()->contains($membership)) {
+            $this->source->getMemberships()[] = $membership;
+            (new self($membership))->addMember($this->source);
+        }
+    }
+
+    public function removeMembership(SourceInterface $membership): void
+    {
+        if ($this->source->getMemberships()->contains($membership)) {
+            $this->source->getMemberships()->removeElement($membership);
+            (new self($membership))->removeMember($this->source);
+        }
+    }
+}
diff --git a/application/src/Domain/SourceManagement/SourceMemberManagerInterface.php b/application/src/Domain/SourceManagement/SourceMemberManagerInterface.php
new file mode 100644
index 0000000..1aeaf54
--- /dev/null
+++ b/application/src/Domain/SourceManagement/SourceMemberManagerInterface.php
@@ -0,0 +1,28 @@
+<?php
+
+namespace App\Domain\SourceManagement;
+
+use App\Entity\Source\SourceInterface;
+
+interface SourceMemberManagerInterface
+{
+    /**
+     * @param SourceInterface $member
+     */
+    public function addMember(SourceInterface $member): void;
+
+    /**
+     * @param SourceInterface $member
+     */
+    public function removeMember(SourceInterface $member): void;
+
+    /**
+     * @param SourceInterface $membership
+     */
+    public function addMembership(SourceInterface $membership): void;
+
+    /**
+     * @param SourceInterface $membership
+     */
+    public function removeMembership(SourceInterface $membership): void;
+}
diff --git a/application/src/Entity/Source/AbstractSource.php b/application/src/Entity/Source/AbstractSource.php
index 65e4e05..c52bf1b 100644
--- a/application/src/Entity/Source/AbstractSource.php
+++ b/application/src/Entity/Source/AbstractSource.php
@@ -103,36 +103,4 @@ abstract class AbstractSource extends AbstractEntity implements SourceInterface
         $this->memberships = new ArrayCollection();
         $this->members = new ArrayCollection();
     }
-
-    public function addMember(SourceInterface $member): void
-    {
-        if (!$this->members->contains($member)) {
-            $this->members[] = $member;
-            $member->addMembership($this);
-        }
-    }
-
-    public function removeMember(SourceInterface $member): void
-    {
-        if ($this->members->contains($member)) {
-            $this->members->removeElement($member);
-            $member->removeMembership($this);
-        }
-    }
-
-    public function addMembership(SourceInterface $membership): void
-    {
-        if (!$this->memberships->contains($membership)) {
-            $this->memberships[] = $membership;
-            $membership->addMember($this);
-        }
-    }
-
-    public function removeMembership(SourceInterface $membership): void
-    {
-        if ($this->memberships->contains($membership)) {
-            $this->memberships->removeElement($membership);
-            $membership->removeMember($this);
-        }
-    }
 }
diff --git a/application/src/Entity/Source/SourceInterface.php b/application/src/Entity/Source/SourceInterface.php
index 9bd3a04..608fa39 100644
--- a/application/src/Entity/Source/SourceInterface.php
+++ b/application/src/Entity/Source/SourceInterface.php
@@ -11,29 +11,8 @@ use App\Entity\Attribut\SlugAttributInterface;
 use App\Entity\Attribut\MembersAttributInterface;
 
 /**
- * @todo Move the members functions to an member ship manager
- *
  * @author kevinfrantz
  */
 interface SourceInterface extends IdAttributInterface, EntityInterface, MembershipsAttributInterface, LawAttributInterface, RelationAttributInterface, SlugAttributInterface, MembersAttributInterface
 {
-    /**
-     * @param SourceInterface $member
-     */
-    public function addMember(SourceInterface $member): void;
-
-    /**
-     * @param SourceInterface $member
-     */
-    public function removeMember(SourceInterface $member): void;
-
-    /**
-     * @param SourceInterface $membership
-     */
-    public function addMembership(SourceInterface $membership): void;
-
-    /**
-     * @param SourceInterface $membership
-     */
-    public function removeMembership(SourceInterface $membership): void;
 }
diff --git a/application/tests/Unit/Domain/SourceManagement/SourceMemberManagerTest.php b/application/tests/Unit/Domain/SourceManagement/SourceMemberManagerTest.php
new file mode 100644
index 0000000..7036b96
--- /dev/null
+++ b/application/tests/Unit/Domain/SourceManagement/SourceMemberManagerTest.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace Tests\Unit\Domain\SourceManagement;
+
+use PHPUnit\Framework\TestCase;
+use App\Entity\Source\SourceInterface;
+use App\Domain\SourceManagement\SourceMemberManagerInterface;
+use App\Entity\Source\AbstractSource;
+use App\Domain\SourceManagement\SourceMemberManager;
+
+class SourceMemberManagerTest extends TestCase
+{
+    /**
+     * @var SourceInterface
+     */
+    private $source;
+
+    /**
+     * @var SourceMemberManagerInterface
+     */
+    private $sourceMemberManager;
+
+    private function createSource(): SourceInterface
+    {
+        return new class() extends AbstractSource {
+        };
+    }
+
+    public function setUp(): void
+    {
+        $this->source = $this->createSource();
+        $this->sourceMemberManager = new SourceMemberManager($this->source);
+    }
+
+    public function testAddAndRemoveMember(): void
+    {
+        $member = $this->createSource();
+        $this->assertNull($this->sourceMemberManager->addMember($member));
+        $this->assertEquals($member, $this->source->getMembers()->get(0));
+        $this->assertEquals($this->source, $member->getMemberships()->get(0));
+        $this->assertNull($this->sourceMemberManager->removeMember($member));
+        $this->assertEquals(0, $this->source->getMembers()->count());
+        $this->assertEquals(0, $member->getMemberships()->count());
+    }
+
+    public function testAddAndRemoveMembership(): void
+    {
+        $membership = $this->createSource();
+        $this->assertNull($this->sourceMemberManager->addMembership($membership));
+        $this->assertEquals($membership, $this->source->getMemberships()->get(0));
+        $this->assertEquals($this->source, $membership->getMembers()->get(0));
+        $this->assertNull($this->sourceMemberManager->removeMembership($membership));
+        $this->assertEquals(0, $this->source->getMemberships()->count());
+        $this->assertEquals(0, $membership->getMembers()->count());
+    }
+}
diff --git a/application/tests/Unit/Entity/Source/AbstractSourceTest.php b/application/tests/Unit/Entity/Source/AbstractSourceTest.php
index 25dbce4..dfb1a98 100644
--- a/application/tests/Unit/Entity/Source/AbstractSourceTest.php
+++ b/application/tests/Unit/Entity/Source/AbstractSourceTest.php
@@ -40,28 +40,6 @@ class AbstractSourceTest extends TestCase
         $this->assertInstanceOf(Collection::class, $this->source->getMembers());
     }
 
-    public function testAddAndRemoveMember(): void
-    {
-        $member = $this->getSourceDummy();
-        $this->assertNull($this->source->addMember($member));
-        $this->assertEquals($member, $this->source->getMembers()->get(0));
-        $this->assertEquals($this->source, $member->getMemberships()->get(0));
-        $this->assertNull($this->source->removeMember($member));
-        $this->assertEquals(0, $this->source->getMembers()->count());
-        $this->assertEquals(0, $member->getMemberships()->count());
-    }
-
-    public function testAddAndRemoveMembership(): void
-    {
-        $membership = $this->getSourceDummy();
-        $this->assertNull($this->source->addMembership($membership));
-        $this->assertEquals($membership, $this->source->getMemberships()->get(0));
-        $this->assertEquals($this->source, $membership->getMembers()->get(0));
-        $this->assertNull($this->source->removeMembership($membership));
-        $this->assertEquals(0, $this->source->getMemberships()->count());
-        $this->assertEquals(0, $membership->getMembers()->count());
-    }
-
     public function testSlugInit(): void
     {
         $this->expectException(\TypeError::class);
diff --git a/application/tests/Unit/Repository/UserSourceRepositoryTest.php b/application/tests/Unit/Repository/UserSourceRepositoryTest.php
index ca4a887..2785f6b 100644
--- a/application/tests/Unit/Repository/UserSourceRepositoryTest.php
+++ b/application/tests/Unit/Repository/UserSourceRepositoryTest.php
@@ -5,6 +5,7 @@ namespace tests\Unit\Repository;
 use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
 use Doctrine\ORM\EntityManager;
 use App\Entity\Source\Complex\UserSource;
+use App\Domain\SourceManagement\SourceMemberManager;
 
 /**
  * @todo refactor this to an integration test!
@@ -30,7 +31,8 @@ class UserSourceRepositoryTest extends KernelTestCase
     {
         $insertSource = new UserSource();
         $origineSource = new UserSource();
-        $origineSource->addMember($insertSource);
+        $origineSourceMemberManager = new SourceMemberManager($origineSource);
+        $origineSourceMemberManager->addMember($insertSource);
         $this->entityManager->persist($insertSource);
         $this->entityManager->persist($origineSource);
         $this->entityManager->flush();
@@ -40,7 +42,7 @@ class UserSourceRepositoryTest extends KernelTestCase
             ->get(0));
         $this->assertEquals($origineSource, $insertSource->getMemberships()
             ->get(0));
-        $this->assertNull($origineSource->removeMember($insertSource));
+        $this->assertNull($origineSourceMemberManager->removeMember($insertSource));
         $this->assertEquals(0, $origineSource->getMembers()
             ->count());
         $this->assertEquals(0, $insertSource->getMemberships()