internal void RemoveMembers(int groupId, IEnumerable <int> userMembers, IEnumerable <int> groupMembers, IEnumerable <int> parentGroups) { _dataProvider.RemoveMembers(groupId, userMembers, groupMembers); if (parentGroups != null) { foreach (var parentGroupId in parentGroups.Distinct()) { _dataProvider.RemoveMembers(parentGroupId, null, new[] { groupId }); } } }