How do I auto populate the Payment Terms in FB01 according to vendor number?

Hi, I was trying to populate the Payment Terms according to the vendor fig oregon relationship fig for the archetypal enactment successful FB01. Tried to make a logic successful GGB1 but the BSEG wrong the customized programme was empty. Therefore, I cannot retrieve the vendor fig oregon relationship number.

Which exit bash I request to modify to populate the Payment Terms?

Assuming that the Account oregon Supplier fig is 1234567. I americium expected that the outgo presumption volition beryllium car populated with 1010. However, it is empty. How and wherever bash I make logic for that since it BSEG-LIFNR is not contiguous erstwhile the customized logic successful GGB1 was called.