Subcontrator Shipment Entry Input Automation

We are starting to utilize the Subcontractor Shipment and Insite functionality to process our subcontract shipments through UPS. We’re trying to simplify the entry process to the point of just typing in a PO# and having the relevant information auto-fill. We’d like to auto-fill the following based on just entering PO#:
Supplier ID
Ship Via
Job Number

Does anyone know of a way to automate this entry process?

A BPM can do this (shouldn’t need code). If you run a trace, it will tell you what method is called when you change the PO (something like SubcontractShip.ChangePONum).
In post processing, you can use an “update table by query” to get you values from the PORel and place them on your record.