I have added a Custom field for our client. But he likes to pull up a report to see what materials are offset against invoices.
On MYOB the old software package they used to use Job numbers (the Job number on the purchase orders being the invoice number) and then he used to pull up a report on Job numbers and this gave him the information of all the products (and parts) used on each sales invoice.
We are after trying to set this up without having to do a project for each sales invoice.
You could enter the same purchase order number in the bill number and run a transaction list by supplier and filter it by bills and purchase orders. This then would show you which PO's and bills are linked.
We appreciate this might not be an ideal solution and therefore to assist us with your requirements, and hopefully get them implemented, we encourage you to leave feedback from within the product.