diff --git a/backend/src/controllers/groups.ts b/backend/src/controllers/groups.ts
index 53bc96ec..217510f6 100644
--- a/backend/src/controllers/groups.ts
+++ b/backend/src/controllers/groups.ts
@@ -3,8 +3,6 @@ import { createGroup, deleteGroup, getAllGroups, getGroup, getGroupSubmissions,
 import { GroupDTO } from '@dwengo-1/common/interfaces/group';
 import { requireFields } from './error-helper.js';
 import { BadRequestException } from '../exceptions/bad-request-exception.js';
-import { EntityDTO } from '@mikro-orm/core';
-import { Group } from '../entities/assignments/group.entity.js';
 
 function checkGroupFields(classId: string, assignmentId: number, groupId: number): void {
     requireFields({ classId, assignmentId, groupId });
@@ -35,7 +33,11 @@ export async function putGroupHandler(req: Request, res: Response): Promise<void
     const groupId = parseInt(req.params.groupid);
     checkGroupFields(classId, assignmentId, groupId);
 
-    const group = await putGroup(classId, assignmentId, groupId, req.body as Partial<EntityDTO<Group>>);
+    // Only members field can be changed
+    const members = req.body.members;
+    requireFields({ members });
+
+    const group = await putGroup(classId, assignmentId, groupId, { members } as Partial<GroupDTO>);
 
     res.json({ group });
 }
diff --git a/backend/src/services/groups.ts b/backend/src/services/groups.ts
index 0c73c8c5..382780d8 100644
--- a/backend/src/services/groups.ts
+++ b/backend/src/services/groups.ts
@@ -7,8 +7,17 @@ import { GroupDTO, GroupDTOId } from '@dwengo-1/common/interfaces/group';
 import { SubmissionDTO, SubmissionDTOId } from '@dwengo-1/common/interfaces/submission';
 import { fetchAssignment } from './assignments.js';
 import { NotFoundException } from '../exceptions/not-found-exception.js';
-import { putObject } from './service-helper.js';
 import { fetchStudents } from './students.js';
+import { fetchClass } from './classes.js';
+import { BadRequestException } from '../exceptions/bad-request-exception.js';
+import { Student } from '../entities/users/student.entity.js';
+import { Class } from '../entities/classes/class.entity.js';
+
+async function assertMembersInClass(members: Student[], cls: Class): Promise<void> {
+    if (!members.every((student) => cls.students.contains(student))) {
+        throw new BadRequestException('Student does not belong to class');
+    }
+}
 
 export async function fetchGroup(classId: string, assignmentNumber: number, groupNumber: number): Promise<Group> {
     const assignment = await fetchAssignment(classId, assignmentNumber);
@@ -28,15 +37,18 @@ export async function getGroup(classId: string, assignmentNumber: number, groupN
     return mapToGroupDTO(group, group.assignment.within);
 }
 
-export async function putGroup(
-    classId: string,
-    assignmentNumber: number,
-    groupNumber: number,
-    groupData: Partial<EntityDTO<Group>>
-): Promise<GroupDTO> {
+export async function putGroup(classId: string, assignmentNumber: number, groupNumber: number, groupData: Partial<GroupDTO>): Promise<GroupDTO> {
     const group = await fetchGroup(classId, assignmentNumber, groupNumber);
 
-    await putObject<Group>(group, groupData, getGroupRepository());
+    const memberUsernames = groupData.members as string[];
+    const members = await fetchStudents(memberUsernames);
+
+    const cls = await fetchClass(classId);
+    await assertMembersInClass(members, cls);
+
+    const groupRepository = getGroupRepository();
+    groupRepository.assign(group, { members } as Partial<EntityDTO<Group>>);
+    await groupRepository.getEntityManager().persistAndFlush(group);
 
     return mapToGroupDTO(group, group.assignment.within);
 }
@@ -63,6 +75,9 @@ export async function createGroup(groupData: GroupDTO, classid: string, assignme
     const memberUsernames = (groupData.members as string[]) || [];
     const members = await fetchStudents(memberUsernames);
 
+    const cls = await fetchClass(classid);
+    await assertMembersInClass(members, cls);
+
     const assignment = await fetchAssignment(classid, assignmentNumber);
 
     const groupRepository = getGroupRepository();
diff --git a/backend/tests/test_assets/assignments/groups.testdata.ts b/backend/tests/test_assets/assignments/groups.testdata.ts
index 16674843..4361383b 100644
--- a/backend/tests/test_assets/assignments/groups.testdata.ts
+++ b/backend/tests/test_assets/assignments/groups.testdata.ts
@@ -61,7 +61,7 @@ export function makeTestGroups(em: EntityManager, students: Student[], assignmen
      */
     group1ConditionalLearningPath = em.create(Group, {
         assignment: getConditionalPathAssignment(),
-        groupNumber: 1,
+        groupNumber: 21005,
         members: [getTestleerling1()],
     });
 
diff --git a/frontend/src/components/MenuBar.vue b/frontend/src/components/MenuBar.vue
index 0954707f..e3734976 100644
--- a/frontend/src/components/MenuBar.vue
+++ b/frontend/src/components/MenuBar.vue
@@ -11,7 +11,7 @@
     const { t, locale } = useI18n();
 
     const role = auth.authState.activeRole;
-    const router = useRouter();
+    const _router = useRouter(); // Zonder '_' gaf dit een linter error voor unused variable
 
     const name: string = auth.authState.user!.profile.name!;
     const initials: string = name