Vbrk xblnr reference sheet

Having some problems trying to get the correct partners from VBPA associated with a sales order from tables VBAK/VBAP. When you maintain your partners at the header level of a sales order in SAP the entries in the partner table do not corrspond with the line items on the sales order. Example: Sales ... FROM VBRK as VK left outer join VBRP as VP ON VK~VBELN = VP~VBELN The collection has been marked as complete with regards to additions. The query works as expected as soon as I comment out the 'VK~NETWR AS BILL_TOTAL' line, but I need to retrieve the contents of the NETWR field in both VBRK and VBRP ... BKPF-XBLNR is usually the field where the Issuer Invoice Number (incoming invoice) is informed. But XBLNR is 16 characters long, which in some cases is not enough to hold the invoice number. The aim of this post is to give a possible solution for Incoming Invoices number length greater than 16 characters.