Display Total PO Amount for Supplier in PO creation page

We have a requirement to display the total PO amount created for a supplier selected in the PO header page. This should retrieve the real-time total amount of the PO raised for the supplier during PO creation.

We attempted using DFF (Default SQL), but were unable to pass supplier_id or po_header_id as binding parameters. Oracle has confirmed that supplier_id or po_header_id cannot be fetched directly from the PO header page.

Could you please advise if there are any alternative approaches to accomplish this requirement