When shipping via Fedex ship manager, there is a way to add reference/PO info to the shipping label, looks like this:
Is there a way to add the reference info to a shipment created in shipstation instead (we would prefer to do these in shipstation but are required to add reference information and for the life of me I can't figure out how to add this information to the shipment.
you can see the answer here
Shipstation Custom Field 1 = FedEx P.O.#
the shipstation order usually goes into the fedex Invoice #
test it out on an order.