How to update PO quantity and date on Drop Ship POs after on-hold invoice is applied?

Summary:

Drop Ship POs are rejecting quantity and date changes when there is an invoice on the PO. The invoices are on hold and un-validated due to e.g missing receipt.

Content (please ensure you mask any confidential information):

Drop Ship POs are rejecting quantity and date changes when there is an invoice on the PO. The invoices are on hold and un-validated due to e.g missing receipt. The system seems to be coded to only allow PO → Receipt→ Invoice flow, this is not the reality. Often suppliers are sending invoices then pushing out delivery or having to cancel quantity on POs. How can this be handled?