Adding shipments using PDOI

We are using 11.5.10.2 with one of the newer purchasing updates and want to automatically add shipments to existing lines of purchase orders previously loaded using PDOI.  The buyers at our feeder plants will not stop adding shipments to existing lines in their systems, which leaves a lot of errors in our regular imports into Oracle EBS.  Is there a way to add shipments to existing standard PO's using any of the interfaces like PDOI?  If not, anyone have any workarounds to suggest?