How to add a Pay site on Purchase Order

Summary: When we Create an EDI Purchase Order, how and where do we include the Pay-to Site information?

Content (please ensure you mask any confidential information):

Our Supplier has multiple Pay sites. When creating a PO, we would like the Buyer to pick the Pay-to Site and include that in the PO, so that when the Supplier sends the Invoice, the Invoice will have the correct Pay Site.

Secondary question - What are some of the ways to determine the Pay-to-site from an Invoice? Where in the EDI do you store the Pay-to Information?

Version (include the version you are using, if applicable):