Supplier Merge - Open POs Only

When a supplier is bought out we have open purchase orders that have not completed their lifecycle. The new supplier will send the invoices for the open orders but the invoice will note the new supplier name. We set up the new supplier and want to perform the merge. Why doesn't Oracle allow to merge only OPEN purchase orders? The old purchase orders need to remain under the old supplier name. Our SOX documents state the supplier name on the purchase order, supplier invoice remit and our check must match. In some instances a buyer may have contract and blanket