How to turn of Supplier communcation for OSP PO's

Summary

We use blanket purchase agreement to communicate with Supplier for OSP services and we don't want to send all the PO's created for Outside processing service to Supplier.

Content

We use blanket purchase agreement to communicate with the Supplier for OSP services and we don't want to send all the PO's created for Outside processing service to the Supplier but we want to communicate the Supplier for PO's( For Ex: Raw materials procured from the vendor) created other than OSP PO's. One possible way of fulfilling this requirement is to Remove the communication for the supplier at the site level and while creating non-OSP PO's enter communication method manually on PO. But doing this so every time is not feasible as the buyer may make the mistake of entering the