Hello Su WM, so having had a look into this more for you, no you won't be able to add a PO to a closed bill. It has to be an open bill, so it means you will have to delete the payment on the bill and add the PO. Once a bill is closed, it is considered finalized and cannot be modified to include a purchase order. So if you have done the reconciliation to include this it is a case of doing the steps you have said to resolve this issue.