Adding 3rd Reference field in Sales/Purchase Ledger transaction against SOP/POPs Customer/Supplier Ord Reference.

When Sales/Purchase order is raised, the customer/supplier Order is entered at SOP/POP order entry level. However when actual invoice is posted via SOP/POP, only Sages order number become available in Sales/Purchase ledger as 2nd ref. Some customer wants to see actual customer/Supplier order ref to be made available in Sales/purchase ledger as 3rd ref No. Hence add 3rd ref field to hold cust/sup order numbers from SOP/POP.