diff --git a/app/Member/Membership.php b/app/Member/Membership.php
index 3423ba8e..48df23cd 100644
--- a/app/Member/Membership.php
+++ b/app/Member/Membership.php
@@ -19,7 +19,7 @@ class Membership extends Model
     use HasNamiField;
 
     /** @var array<int, string> */
-    public $fillable = ['subactivity_id', 'activity_id', 'group_id', 'member_id', 'nami_id', 'from', 'to', 'promised_at'];
+    public $guarded = [];
 
     /** @var array<string, string> */
     public $casts = [
diff --git a/app/Membership/Actions/MembershipStoreAction.php b/app/Membership/Actions/MembershipStoreAction.php
index b3342a49..dbccb97e 100644
--- a/app/Membership/Actions/MembershipStoreAction.php
+++ b/app/Membership/Actions/MembershipStoreAction.php
@@ -3,6 +3,7 @@
 namespace App\Membership\Actions;
 
 use App\Activity;
+use App\Group;
 use App\Member\Member;
 use App\Member\Membership;
 use App\Setting\NamiSettings;
@@ -21,7 +22,7 @@ class MembershipStoreAction
 {
     use AsAction;
 
-    public function handle(Member $member, Activity $activity, ?Subactivity $subactivity, ?Carbon $promisedAt, NamiSettings $settings): Membership
+    public function handle(Member $member, Activity $activity, ?Subactivity $subactivity, Group $group, ?Carbon $promisedAt, NamiSettings $settings): Membership
     {
         $from = now()->startOfDay();
 
@@ -31,7 +32,7 @@ class MembershipStoreAction
             try {
                 $namiId = $settings->login()->putMembership($member->nami_id, NamiMembership::from([
                     'startsAt' => $from,
-                    'groupId' => $member->group->nami_id,
+                    'groupId' => $group->nami_id,
                     'activityId' => $activity->nami_id,
                     'subactivityId' => $subactivity->nami_id,
                 ]));
@@ -44,7 +45,9 @@ class MembershipStoreAction
             'activity_id' => $activity->id,
             'subactivity_id' => $subactivity->id,
             'promised_at' => $promisedAt,
-            ...['nami_id' => $namiId ?? null, 'group_id' => $member->group->id, 'from' => $from],
+            'group_id' => $group->id,
+            'from' => $from,
+            'nami_id' => $namiId ?? null,
         ]);
 
         if ($activity->hasNami && ($subactivity->id === null || $subactivity->hasNami)) {
@@ -85,6 +88,7 @@ class MembershipStoreAction
             $member,
             Activity::find($request->activity_id),
             $request->subactivity_id ? Subactivity::find($request->subactivity_id) : null,
+            Group::findOrFail($request->input('group_id', -1)),
             $request->promised_at ? Carbon::parse($request->promised_at) : null,
             $settings,
         );
diff --git a/packages/laravel-nami b/packages/laravel-nami
index 0ee77550..315be84c 160000
--- a/packages/laravel-nami
+++ b/packages/laravel-nami
@@ -1 +1 @@
-Subproject commit 0ee77550774715324e2fa66ca2b821d8a0e19880
+Subproject commit 315be84cf38f1a01f890180099d3b2156bf344b9
diff --git a/tests/Feature/Membership/StoreTest.php b/tests/Feature/Membership/StoreTest.php
index d85b4256..de2715fc 100644
--- a/tests/Feature/Membership/StoreTest.php
+++ b/tests/Feature/Membership/StoreTest.php
@@ -42,7 +42,7 @@ class StoreTest extends TestCase
 
         $response = $this->from('/member')->post(
             "/member/{$member->id}/membership",
-            MembershipRequestFactory::new()->promise(now())->in($activity, $activity->subactivities->first())->create()
+            MembershipRequestFactory::new()->promise(now())->in($activity, $activity->subactivities->first())->group($member->group)->create()
         );
 
         $response->assertRedirect('/member');
@@ -53,6 +53,7 @@ class StoreTest extends TestCase
             'subactivity_id' => $activity->subactivities->first()->id,
             'nami_id' => 133,
             'promised_at' => now()->format('Y-m-d'),
+            'group_id' => $member->group->id,
         ]);
         app(MembershipFake::class)->assertCreated(6, [
             'untergliederungId' => 4,
@@ -75,7 +76,7 @@ class StoreTest extends TestCase
 
         $this->from('/member')->post(
             "/member/{$member->id}/membership",
-            MembershipRequestFactory::new()->in($activity, $activity->subactivities->first())->create()
+            MembershipRequestFactory::new()->in($activity, $activity->subactivities->first())->group($member->group)->create()
         );
 
         $this->assertDatabaseHas('memberships', [
@@ -98,7 +99,7 @@ class StoreTest extends TestCase
 
         $this->from('/member')->post(
             "/member/{$member->id}/membership",
-            MembershipRequestFactory::new()->in($activity, $activity->subactivities->first())->create()
+            MembershipRequestFactory::new()->in($activity, $activity->subactivities->first())->group($member->group)->create()
         );
 
         $this->assertDatabaseHas('memberships', [
@@ -157,6 +158,27 @@ class StoreTest extends TestCase
         $this->assertErrors(['subactivity_id' => 'Untertätigkeit ist nicht vorhanden.'], $response);
     }
 
+    public function testItCanAddAnotherGroup(): void
+    {
+        app(MembershipFake::class)->createsSuccessfully(6, 133);
+        app(MemberFake::class)->shows(1400, 6, ['version' => 1506]);
+        $member = Member::factory()->defaults()->for(Group::factory()->inNami(1400))->inNami(6)->create();
+        $group = Group::factory()->inNami(1401)->create();
+        $activity = Activity::factory()->inNami(7)->hasAttached(Subactivity::factory()->inNami(8))->create();
+
+        $this->post(
+            "/member/{$member->id}/membership",
+            MembershipRequestFactory::new()->in($activity, $activity->subactivities->first())->group($group)->create()
+        );
+
+        $this->assertDatabaseHas('memberships', [
+            'group_id' => $group->id,
+        ]);
+        app(MembershipFake::class)->assertCreated(6, [
+            'gruppierungId' => 1401,
+        ]);
+    }
+
     public function testSubactivityCanBeEmpty(): void
     {
         $this->withoutExceptionHandling();
@@ -173,7 +195,7 @@ class StoreTest extends TestCase
 
         $this->post(
             "/member/{$member->id}/membership",
-            MembershipRequestFactory::new()->in($activity, null)->create()
+            MembershipRequestFactory::new()->in($activity, null)->group($member->group)->create()
         );
 
         $this->assertEquals(1506, $member->fresh()->version);
@@ -211,7 +233,7 @@ class StoreTest extends TestCase
 
         $response = $this->post(
             "/member/{$member->id}/membership",
-            MembershipRequestFactory::new()->in($activity, $activity->subactivities->first())->create()
+            MembershipRequestFactory::new()->in($activity, $activity->subactivities->first())->group($member->group)->create()
         );
 
         $this->assertErrors(['nami' => $validationError], $response);
diff --git a/tests/Feature/Membership/UpdateTest.php b/tests/Feature/Membership/UpdateTest.php
index 3ad327e5..16c503f6 100644
--- a/tests/Feature/Membership/UpdateTest.php
+++ b/tests/Feature/Membership/UpdateTest.php
@@ -24,7 +24,7 @@ class UpdateTest extends TestCase
         $this->login()->loginNami();
     }
 
-    public function testItCreatesAMembership(): void
+    public function testItUpdatesAMembership(): void
     {
         $this->withoutExceptionHandling();
         $activity = Activity::factory()->hasAttached(Subactivity::factory())->create();
diff --git a/tests/RequestFactories/MembershipRequestFactory.php b/tests/RequestFactories/MembershipRequestFactory.php
index d6183046..fe227e87 100644
--- a/tests/RequestFactories/MembershipRequestFactory.php
+++ b/tests/RequestFactories/MembershipRequestFactory.php
@@ -3,6 +3,7 @@
 namespace Tests\RequestFactories;
 
 use App\Activity;
+use App\Group;
 use App\Subactivity;
 use Carbon\Carbon;
 use Worksome\RequestFactories\RequestFactory;
@@ -54,4 +55,9 @@ class MembershipRequestFactory extends RequestFactory
             'promised_at' => $value->format('Y-m-d'),
         ]);
     }
+
+    public function group(Group $group): self
+    {
+        return $this->state(['group_id' => $group->id]);
+    }
 }