We manage records in the data mirror using our business partner id. This one is used as the external id for uniquely identifying records in the data mirror.
In our local system this business partner can have 1 or more supplier or customer ids. We'd need to map these identifiers to your data model for having the info available, e.g. in lookup use cases to get to know where and how the partner is used locally in our systems
Mapping and Display of multiple external IDs
Merged