AP Vendor's payment address

Hello, hope some can help me out here. We have a custom program that creates a vendor's payment history report. It reports vendors ID, name, tax ID, invoice amt, Net Payment Amount, class, and address. The only problem is the some of the address are incorrect because they want to see not the main address but the transaction address. So if a vendor's main address is in IL, but they did the transaction in WNY, the it should report the WNY address. I don't know where this address would be store other than the AP vendoradress file.