Create Supplier REST API Specify Creation Source

Summary:

We have two distinct interfaces to Create Supplier records both utilise the same Create Supplier REST API we would like to stamp the suppliers who get created with a source to specify which interface created them.

Presently when using the Create Supplier REST Api you are not able to specify the source it defaults to WEB_SERVICE based on the lookup_type POZ_CREATION_SOURCE.

Is there anyone to achieve this via adding records to the Lookup and then being able to specify the code during the API call? Or would we need to implement this via using a DFF field and leaving the source field as it is.