Is there a way to add a new line item to an existing PO against a BPA source agreement

Summary:

We have alot of customers you have the need to add a line item to an exist PO that was issued against a BPA. Currently when we try to do this the BPA number/BPA line item does not show up to add it to the line item. One work around we have been using is the requestor creates a another PO against that agreement and then asks Procurement to cancel the new PO, the buyer then takes the requisition and adds to existing BPA release PO. This is a cumbersome process and very