We have a specific vendor who does not have SAP codes established (so I can't manage through an info record). We need all purchase order line items with that vendor to allow 20% over delivery. Is that possible, without creating SAP material numbers?
You can't define over delivery tolerances on vendor level only. If you don't work with material numbers and info records, then you can set up the tolerances in purchase order items manually. That can be automated with the ME_PROCESS_PO_CUST BAdI enhancement.