When does VBPA-ADRNR gets updated?

Hi All,

We have a case in which in the invoice output ,delivery address appearing is incorrect(for one customer only,rest all customers address display is correct).When checked we could find that address number appearing in VBPA table is wrong.that is why a incorrect address is displayed.

So I want to check why a wrong address number is updated in the VBPA table.

the document flow is,

PO-Delivery-Invoice.

where i will check for the updation of address number in vbpa??

any user-exits??

awaiting reply......