Generating a detailed A/P aging report with correct expense codes applied

At present we still get our accountant to generate monthly P/L for us, so we send them a coded creditors report (not for much longer!)
I am trying to get that report out of NS, so customized the A/P aging report to include the column ACCOUNT (LINE): NUMBER.  This does a fantastic job of showing the coding, but where we have created an item receipt for inbound inventory, those transaction lines show on the A/P report as the 'inventory received not billed' code, and happens on every inventory item, even where the bill has been created before the item receipt.  The ledger does show the entry being reversed out of inventory received not billed, but despite the A/P report date being set to well after