Oracle Order Management - how can I systematically associate the Original Order Number to Bill Only

Today when we create a bill only, credit only or a return order, we create them by copying the original order number.  In our business there are times when we need to create additional bill only and credit only orders.  Oracle does not allow this by copying the original order again, therefore our customer service users created a bill only, credit only or a return by creating a new order and changing the order type.  When they do this, we are no longer able to tie these orders back to the original order numbers.  Is there a good way to