Is it possible to send same purchase order to main vendor as well as well the freight vendor on two different AN ID i.e main vendor should only receive the PO regarding the procurement line item and conditional (Freight ) vendor receive only freight information. If yes then can the freight vendor generate the invoice for the same.
Typically you would want to have one Purchase Requisition (PR) which splits into multiple Purchase Orders (PO) based on line item conditions.
Only one PO number can belong to one vendor. The same PO number can not belong to multiple vendors at the line item level. Additionally, the suppliers location and preferred ordering method will cause the PR to split into multiple POs.