Bill-to-PO Matching: How can I match a Bill to a Purchase Order after the invoice has been approved or paid?

Bill-to-PO Matching: How can I match a Bill to a Purchase Order after the invoice has been approved or paid?

Matching is only possible up to the point where a Purchase Order gets marked as "Billed " (*) / a Bill is "Approved".
Once this has taken place, only an Administrator has the authority to unmatch/change the matching.

(*) The marking as "Billed" can be revised by the Organisation's Administrator or the Purchase Order Requester.