currently the only place you can enter the supplier invoice number is when you update the ledger in the EX.Ref box. If you do a supplier purchase payment you would normally match this to their statement and the total amount to pay, but if in sage you de-select "list invoice by item line" to see the total amount only, then their invoice number does not get printed on the remittance. This means they have no-idea what the amount is referenced to.