You want to get all users from a group or groups for an user.
Getting users of a group or groups for an user is done in similar way – through AxUserAuthorizationAdapter.LoadUserMembership(int userId, byte UserType) method. Depending on passed UserType argument, the method will retrieve either list of id’s of groups of user, or list of id's of users in a group.
// getting groups for a user
int groupsIDList = (new AxUserAuthorizationAdapter()).LoadUserMembership(userID, (byte) UserType.Group);
// getting users of a group
int usersIDList = (new
Same technique applies in MS and LS.