diff --git a/app/Actions/InsertMembershipsAction.php b/app/Actions/InsertMembershipsAction.php
index 959f05ff..301ab989 100644
--- a/app/Actions/InsertMembershipsAction.php
+++ b/app/Actions/InsertMembershipsAction.php
@@ -79,7 +79,7 @@ class InsertMembershipsAction
     private function singleStrategy(Member $member, Group $group, NamiMembershipEntry $membershipEntry): ?Membership
     {
         $membership = $this->api()->membership($member->nami_id, $membershipEntry->id);
-        app(ActivityCreator::class)->createFor($this->api(), $membership->groupId);
+        app(ActivityCreator::class)->createFor($this->api(), $membership->group());
 
         $activity = Activity::nami($membership->activityId);
         if (!$activity) {
diff --git a/app/Activity/Actions/ActivityUpdateAction.php b/app/Activity/Actions/ActivityUpdateAction.php
index 8ae53f60..1f45ead2 100644
--- a/app/Activity/Actions/ActivityUpdateAction.php
+++ b/app/Activity/Actions/ActivityUpdateAction.php
@@ -10,10 +10,16 @@ use Illuminate\Validation\ValidationException;
 use Lorisleiva\Actions\ActionRequest;
 use Lorisleiva\Actions\Concerns\AsAction;
 
+/**
+ * @template Payload of array{name: string, subactivities: array<int, int>}
+ */
 class ActivityUpdateAction
 {
     use AsAction;
 
+    /**
+     * @param Payload $payload
+     */
     public function handle(Activity $activity, array $payload): void
     {
         DB::transaction(function() use ($activity, $payload) {
@@ -22,6 +28,9 @@ class ActivityUpdateAction
         });
     }
 
+    /**
+     * @return array<string, string>
+     */
     public function rules(): array
     {
         return [
@@ -43,20 +52,21 @@ class ActivityUpdateAction
 
     /**
      * @todo handle this with a model event on the pivot model
+     * @param Payload $payload
      */
     private function validateNami(Activity $activity, array $payload): void
     {
-        if ($activity->name !== data_get($payload, 'name', '')) {
+        if ($activity->name !== $payload['name']) {
             throw ValidationException::withMessages(['nami_id' => 'Aktivität ist in NaMi. Update des Namens nicht möglich.']);
         }
 
-        $removingSubactivities = $activity->subactivities()->whereNotIn('id', data_get($payload, 'subactivities'))->pluck('id');
+        $removingSubactivities = $activity->subactivities()->whereNotIn('id', $payload['subactivities'])->pluck('id');
 
         if ($removingSubactivities->first(fn ($subactivity) => Subactivity::find($subactivity)->hasNami)) {
             throw ValidationException::withMessages(['nami_id' => 'Untertätigkeit kann nicht entfernt werden.']);
         }
 
-        $addingSubactivities = collect(data_get($payload, 'subactivities'))->filter(fn ($subactivityId) => $activity->subactivities->doesntContain($subactivityId));
+        $addingSubactivities = collect($payload['subactivities'])->filter(fn ($subactivityId) => $activity->subactivities->doesntContain($subactivityId));
 
         if ($addingSubactivities->first(fn ($subactivity) => Subactivity::find($subactivity)->hasNami)) {
             throw ValidationException::withMessages(['nami_id' => 'Untertätigkeit kann nicht hinzugefügt werden.']);
diff --git a/app/Initialize/ActivityCreator.php b/app/Initialize/ActivityCreator.php
index fb9d5b92..f0f170a5 100644
--- a/app/Initialize/ActivityCreator.php
+++ b/app/Initialize/ActivityCreator.php
@@ -3,6 +3,7 @@
 namespace App\Initialize;
 
 use Zoomyboy\LaravelNami\Api;
+use Zoomyboy\LaravelNami\Data\Group;
 
 class ActivityCreator
 {
@@ -50,10 +51,10 @@ class ActivityCreator
         '€ LeiterIn',
     ];
 
-    public function createFor(Api $api, int $groupId): void
+    public function createFor(Api $api, Group $groupId): void
     {
-        $api->activities($groupId)->each(function ($activity) use ($api) {
-            $activity = \App\Activity::updateOrCreate(['nami_id' => $activity->id], [
+        $api->activities($groupId)->each(function ($activity) {
+            $localActivity = \App\Activity::updateOrCreate(['nami_id' => $activity->id], [
                 'nami_id' => $activity->id,
                 'name' => $activity->name,
                 'is_try' => in_array($activity->name, $this->tries),
@@ -63,7 +64,7 @@ class ActivityCreator
             ]);
 
             $groups = [];
-            $api->subactivitiesOf($activity->nami_id)->each(function ($group) use (&$groups) {
+            $activity->subactivities()->each(function ($group) use (&$groups) {
                 $group = \App\Subactivity::updateOrCreate(['nami_id' => $group->id], [
                     'nami_id' => $group->id,
                     'name' => $group->name,
@@ -72,7 +73,7 @@ class ActivityCreator
                 ]);
                 $groups[] = $group->id;
             });
-            $activity->subactivities()->sync($groups);
+            $localActivity->subactivities()->sync($groups);
         });
     }
 }
diff --git a/app/Initialize/InitializeActivities.php b/app/Initialize/InitializeActivities.php
index f1fe452c..7f485c00 100644
--- a/app/Initialize/InitializeActivities.php
+++ b/app/Initialize/InitializeActivities.php
@@ -2,7 +2,7 @@
 
 namespace App\Initialize;
 
-use DB;
+use Illuminate\Support\Facades\DB;
 use Zoomyboy\LaravelNami\Api;
 
 class InitializeActivities
@@ -16,8 +16,7 @@ class InitializeActivities
 
     public function handle(): void
     {
-        $groupId = $this->api->groups()->first()->id;
-        app(ActivityCreator::class)->createFor($this->api, $groupId);
+        app(ActivityCreator::class)->createFor($this->api, $this->api->groups()->first());
     }
 
     public function restore(): void
diff --git a/app/Initialize/InitializeGroups.php b/app/Initialize/InitializeGroups.php
index d4023b11..880b12b0 100644
--- a/app/Initialize/InitializeGroups.php
+++ b/app/Initialize/InitializeGroups.php
@@ -5,6 +5,7 @@ namespace App\Initialize;
 use App\Group;
 use DB;
 use Zoomyboy\LaravelNami\Api;
+use Zoomyboy\LaravelNami\Data\Group as NamiGroup;
 
 class InitializeGroups
 {
@@ -17,18 +18,18 @@ class InitializeGroups
 
     public function handle(): void
     {
-        $this->api->groups()->each(function ($group) {
+        $this->api->groups(null)->each(function ($group) {
             $parent = Group::updateOrCreate(['nami_id' => $group->id], ['nami_id' => $group->id, 'name' => $group->name]);
 
-            $this->syncChildren($group->id, $parent);
+            $this->syncChildren($group, $parent);
         });
     }
 
-    private function syncChildren(int $groupId, Group $parent): void
+    private function syncChildren(NamiGroup $namiParent, Group $parent): void
     {
-        $this->api->subgroupsOf($groupId)->each(function ($subgroup) use ($parent) {
+        $this->api->groups($namiParent)->each(function ($subgroup) use ($parent) {
             $newParent = Group::updateOrCreate(['nami_id' => $subgroup->id], ['nami_id' => $subgroup->id, 'name' => $subgroup->name, 'parent_id' => $parent->id]);
-            $this->syncChildren($subgroup->id, $newParent);
+            $this->syncChildren($subgroup, $newParent);
         });
     }
 
diff --git a/packages/laravel-nami b/packages/laravel-nami
index 07d1e676..3c3d0df5 160000
--- a/packages/laravel-nami
+++ b/packages/laravel-nami
@@ -1 +1 @@
-Subproject commit 07d1e67698ef09fe274a35f3d822ef3dd526ff22
+Subproject commit 3c3d0df50e56ce09a09f8624e9491fdd43369dfa
diff --git a/phpstan.neon b/phpstan.neon
index 2aa16f05..8b4fe328 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -294,31 +294,6 @@ parameters:
             count: 1
             path: tests/Unit/Mailman/ServiceTest.php
 
-        -
-            message: "#^Method Zoomyboy\\\\LaravelNami\\\\Activity\\:\\:fromNami\\(\\) has no return type specified\\.$#"
-            count: 1
-            path: packages/laravel-nami/src/Activity.php
-
-        -
-            message: "#^Method Zoomyboy\\\\LaravelNami\\\\Activity\\:\\:fromNami\\(\\) has parameter \\$item with no type specified\\.$#"
-            count: 1
-            path: packages/laravel-nami/src/Activity.php
-
-        -
-            message: "#^Method Zoomyboy\\\\LaravelNami\\\\Activity\\:\\:subactivities\\(\\) has no return type specified\\.$#"
-            count: 1
-            path: packages/laravel-nami/src/Activity.php
-
-        -
-            message: "#^Unable to resolve the template type TKey in call to function collect$#"
-            count: 1
-            path: packages/laravel-nami/src/Activity.php
-
-        -
-            message: "#^Unable to resolve the template type TValue in call to function collect$#"
-            count: 1
-            path: packages/laravel-nami/src/Activity.php
-
         -
             message: "#^Property Zoomyboy\\\\LaravelNami\\\\Authentication\\\\FakeCookie\\:\\:\\$authenticated type has no value type specified in iterable type array\\.$#"
             count: 1
@@ -459,21 +434,6 @@ parameters:
             count: 1
             path: packages/laravel-nami/src/Gender.php
 
-        -
-            message: "#^Method Zoomyboy\\\\LaravelNami\\\\Group\\:\\:fees\\(\\) has no return type specified\\.$#"
-            count: 1
-            path: packages/laravel-nami/src/Group.php
-
-        -
-            message: "#^Method Zoomyboy\\\\LaravelNami\\\\Group\\:\\:fromResponse\\(\\) has parameter \\$response with no value type specified in iterable type array\\.$#"
-            count: 1
-            path: packages/laravel-nami/src/Group.php
-
-        -
-            message: "#^Method Zoomyboy\\\\LaravelNami\\\\Group\\:\\:subgroups\\(\\) has no return type specified\\.$#"
-            count: 1
-            path: packages/laravel-nami/src/Group.php
-
         -
             message: "#^Method Zoomyboy\\\\LaravelNami\\\\Logger\\:\\:__construct\\(\\) has parameter \\$options with no type specified\\.$#"
             count: 1
@@ -674,41 +634,6 @@ parameters:
             count: 1
             path: packages/laravel-nami/src/Region.php
 
-        -
-            message: "#^Call to an undefined static method Zoomyboy\\\\LaravelNami\\\\Subactivity\\:\\:getNullValue\\(\\)\\.$#"
-            count: 1
-            path: packages/laravel-nami/src/Subactivity.php
-
-        -
-            message: "#^Method Zoomyboy\\\\LaravelNami\\\\Subactivity\\:\\:fromNami\\(\\) has no return type specified\\.$#"
-            count: 1
-            path: packages/laravel-nami/src/Subactivity.php
-
-        -
-            message: "#^Method Zoomyboy\\\\LaravelNami\\\\Subactivity\\:\\:fromNami\\(\\) has parameter \\$item with no type specified\\.$#"
-            count: 1
-            path: packages/laravel-nami/src/Subactivity.php
-
-        -
-            message: "#^Method Zoomyboy\\\\LaravelNami\\\\Subactivity\\:\\:getIsNullAttribute\\(\\) has no return type specified\\.$#"
-            count: 1
-            path: packages/laravel-nami/src/Subactivity.php
-
-        -
-            message: "#^Method Zoomyboy\\\\LaravelNami\\\\Subactivity\\:\\:getNameAttribute\\(\\) has no return type specified\\.$#"
-            count: 1
-            path: packages/laravel-nami/src/Subactivity.php
-
-        -
-            message: "#^Unable to resolve the template type TKey in call to function collect$#"
-            count: 1
-            path: packages/laravel-nami/src/Subactivity.php
-
-        -
-            message: "#^Unable to resolve the template type TValue in call to function collect$#"
-            count: 1
-            path: packages/laravel-nami/src/Subactivity.php
-
         -
             message: "#^Method Zoomyboy\\\\LaravelNami\\\\Tests\\\\Stub\\\\Member\\:\\:findByNamiId\\(\\) has no return type specified\\.$#"
             count: 1
diff --git a/tests/Unit/InitializeGroupsTest.php b/tests/Unit/InitializeGroupsTest.php
index 21575936..20bd0ec6 100644
--- a/tests/Unit/InitializeGroupsTest.php
+++ b/tests/Unit/InitializeGroupsTest.php
@@ -8,7 +8,7 @@ use Illuminate\Foundation\Testing\DatabaseTransactions;
 use PHPUnit\Framework\MockObject\Stub;
 use Tests\TestCase;
 use Zoomyboy\LaravelNami\Api;
-use Zoomyboy\LaravelNami\Group;
+use Zoomyboy\LaravelNami\Data\Group;
 
 class InitializeGroupsTest extends TestCase
 {
@@ -34,13 +34,12 @@ class InitializeGroupsTest extends TestCase
 
     public function testItSynchsAGroupWithASingleNodeAndNoChildren(): void
     {
+        $parentGroup = Group::from(['id' => 150, 'name' => 'lorem', 'parentId' => null]);
         $this->api->method('groups')->will($this->returnValueMap([
-            [
-                null,
-                collect([(new Group())->setParentId(null)->setId(150)->setName('lorem')]),
-            ],
+            [null, collect([$parentGroup])],
+            [$parentGroup, collect([])],
         ]));
-        $this->api->method('subgroupsOf')->willReturn(collect([]));
+        $this->api->method('groups')->willReturn(collect([]));
 
         (new InitializeGroups($this->api))->handle();
 
@@ -54,13 +53,11 @@ class InitializeGroupsTest extends TestCase
     public function testItDoesntCreateAGroupTwiceWithTheSameNamiId(): void
     {
         GroupModel::factory()->create(['nami_id' => 150]);
+        $parentGroup = Group::from(['id' => 150, 'name' => 'lorem', 'parentId' => null]);
         $this->api->method('groups')->will($this->returnValueMap([
-            [
-                null,
-                collect([(new Group())->setParentId(null)->setId(150)->setName('lorem')]),
-            ],
+            [null, collect([$parentGroup])],
+            [$parentGroup, collect([])],
         ]));
-        $this->api->method('subgroupsOf')->willReturn(collect([]));
 
         (new InitializeGroups($this->api))->handle();
 
@@ -69,17 +66,13 @@ class InitializeGroupsTest extends TestCase
 
     public function testItSynchsSubgroups(): void
     {
-        GroupModel::factory()->create(['nami_id' => 150]);
-        $this->api->method('groups')->willReturn(
-            collect([(new Group())->setParentId(null)->setId(150)->setName('lorem')])
-        );
-        $this->api->method('subgroupsOf')->willReturnCallback(function ($groupId) {
-            if (150 === $groupId) {
-                return collect([(new Group())->setParentId(150)->setId(200)->setName('subgroup')]);
-            }
-
-            return collect([]);
-        });
+        $parentGroup = Group::from(['id' => 150, 'name' => 'lorem', 'parentId' => null]);
+        $subgroup = Group::from(['id' => 200, 'name' => 'subgroup', 'parentId' => 150]);
+        $this->api->method('groups')->will($this->returnValueMap([
+            [null, collect([$parentGroup])],
+            [$parentGroup, collect([$subgroup])],
+            [$subgroup, collect([])],
+        ]));
 
         (new InitializeGroups($this->api))->handle();
 
@@ -91,20 +84,15 @@ class InitializeGroupsTest extends TestCase
 
     public function testItSynchsSubgroupsOfSubgroups(): void
     {
-        GroupModel::factory()->create(['nami_id' => 150]);
-        $this->api->method('groups')->willReturn(
-            collect([(new Group())->setParentId(null)->setId(150)->setName('lorem')])
-        );
-        $this->api->method('subgroupsOf')->willReturnCallback(function ($groupId) {
-            if (150 === $groupId) {
-                return collect([(new Group())->setParentId(150)->setId(200)->setName('subgroup')]);
-            }
-            if (200 === $groupId) {
-                return collect([(new Group())->setParentId(200)->setId(201)->setName('subsubgroup')]);
-            }
-
-            return collect([]);
-        });
+        $parentGroup = Group::from(['id' => 150, 'name' => 'lorem', 'parentId' => null]);
+        $subgroup = Group::from(['id' => 200, 'name' => 'subgroup', 'parentId' => 150]);
+        $subsubgroup = Group::from(['id' => 250, 'name' => 'subsubgroup', 'parentId' => 200]);
+        $this->api->method('groups')->will($this->returnValueMap([
+            [null, collect([$parentGroup])],
+            [$parentGroup, collect([$subgroup])],
+            [$subgroup, collect([$subsubgroup])],
+            [$subsubgroup, collect([])],
+        ]));
 
         (new InitializeGroups($this->api))->handle();
 
@@ -114,16 +102,13 @@ class InitializeGroupsTest extends TestCase
     public function testItAssignsIdAndParentToAnExistingSubgroup(): void
     {
         GroupModel::factory()->create(['nami_id' => 200]);
-        $this->api->method('groups')->willReturn(
-            collect([(new Group())->setParentId(null)->setId(150)->setName('root')])
-        );
-        $this->api->method('subgroupsOf')->willReturnCallback(function ($groupId) {
-            if (150 === $groupId) {
-                return collect([(new Group())->setParentId(150)->setId(200)->setName('child')]);
-            }
-
-            return collect([]);
-        });
+        $parentGroup = Group::from(['id' => 150, 'name' => 'root', 'parentId' => null]);
+        $subgroup = Group::from(['id' => 200, 'name' => 'child', 'parentId' => 150]);
+        $this->api->method('groups')->will($this->returnValueMap([
+            [null, collect([$parentGroup])],
+            [$parentGroup, collect([$subgroup])],
+            [$subgroup, collect([])],
+        ]));
 
         (new InitializeGroups($this->api))->handle();