Where to get Code to check why FBDI Import Blanket Agreement not updating few columns like Supplier

Summary

Where to get Code to check why FBDI Import Blanket Agreement not updating few columns like Supplier Aux Id

Content

Hi ,

We are updating columns of BPA line through FBDI, few columns are updating few not. Not updating  Supplier Auxilary Id. Price gets updated. Now I need to check BPA import code why not updating.

Can you guide where and how to check codes.