private void Fixupcustomer_status(customer_status previousValue) { if (previousValue != null && previousValue.customers.Contains(this)) { previousValue.customers.Remove(this); } if (customer_status != null) { if (!customer_status.customers.Contains(this)) { customer_status.customers.Add(this); } if (status_id != customer_status.id) { status_id = customer_status.id; } } }