Drop ship with quantity variance on AP invoice

Summary:

Sales order created for quantity of 1, but drop ship supplier shipped and billed 5.

Content (required):

We have a situation where a customer will order a quantity that may be less than a drop ship supplier shipped. The PO is sent to the supplier automatically and we do not communicate PO changes. When the AP invoice comes in, we are billed a greater quantity than requested. However, upon contact with customer, they agree to accept additional quantity.

We have a global procurement business unit that is separate from selling business unit and have configured financial orchestration to transfer costs based on the transaction cost. We need to be able to update the sales order and related purchase order to clear the AP match variance.