How to assign Tax Registration numbers for supplier at Address/ Site Level through FBDI load?

Summary

The Supplier is having multiple tax registration number at Site level in their legacy system. How can we assign the same at Address/Site level through data migration using FBDI?

Content

The client is having multiple Tax Registration Number maintained at site level in their legacy system. The Supplier Address has the field Tax registration Number in UI. But in FBDI, I don't see the same in Supplier Address file. But even at Supplier Site FBDI, the tax registration number field is Obsolete. How can we load the multiple tax registration number for the same supplier maintained at site level during data migration?