LTL EDI - SCAC field gets overwritten

This could happen with any mode, but is impactful to LTL EDI.

When an Order is sent to Navix, we use the information contained to update the Vendor record. For LTL where we're receiving EDI invoices and retrieving docs, the SCAC is a key part of that transaction. Can we 1) add a check box to a vendor to not allow the SCAC to be overwritten via integration (i.e. manually only), 2) force all SCACs to be manually overwritten once they exist on the Vendor record, or 3) use a different field for the EDI / SMC3 integrations that isn't overwritten?

Options to accomplish this, but by doing something like this we could prevent an upstream user from having a detrimental impact on receiving invoices or retrieving docs via SMC3.