private void Fixupstaff(staff previousValue) { if (previousValue != null && previousValue.email_history.Contains(this)) { previousValue.email_history.Remove(this); } if (staff != null) { if (!staff.email_history.Contains(this)) { staff.email_history.Add(this); } if (staff_id != staff.id) { staff_id = staff.id; } } else if (!_settingFK) { staff_id = null; } }