I want to automatically update the Customer PO of an order in Internal Sales Order (IRISO)

Oracle EBS R12.2+ (PO Requisitions Interface for IR to ISO, OE_ORDER_PUB API)

We have a business process where we're creating an Internal Requisition that then becomes an Internal Sales Order for a consignment shipment of inventory. The destination warehouse requires a reference number to be on the shipping paperwork, and it is referenced as a customer PO number on their requirements, and our normal shipment processes automatically has this field shown on the bill of lading.

The issue seems to be that the PO Requisition process does not employ a way of getting a customer PO to the ISO that is generated from the IR. The OE_ORDER_PUB package's "update_header" procedure does not have cust_po_number as an updateable field.