Earlier this week I ran into the ‘missing feature’ in Epicor to be able to assign Buyer’s by Supplier. This is an idea out there that is still gauging interest, please vote it up!
The Idea:
Add BUYER to the Supplier tables, and add to | Epicor Ideas Portal
Forum Thread on the topic: Assign buyer to supplier for PO Suggestions - Epicor ERP 10 - Epicor User Help Forum