Need to turn off auto sourcing for non catalog requisitions

Currently we auto generate orders on all catalog items, meaning if the item exists with a PIM item number, and is attached to a bpa.

Recently we realized that if someone puts in a non catalog request the system is auto matching based on the supplier part number and assigning the corresponding item even if the requester did not submit this way. This is a problem because we are attempting to bypass EDI in some cases where we need to place emergency overnight orders.

Is there a way to stop that smart match on the supplier part number feature? If so, I would like to turn it off so that only catalog orders are able to automatically generate and all non catalog must stop at a buyer for processing.