Canceled balance on PO when there are Open Receipts that have not been vouchered - cannot reverse

Scenario:

JDE E1 - 9.1

User received a partial amount from a purchase order line.  That receipt is still open...has not been voucher matched. [P43214]

User then canceled the purchase order in full (balance on the PO). [P4310]

The open Receipt amount is wrong...User tried to reverse this receipt & receives an error message that the 'Record is Invalid' --- because the PO has now been canceled.

Is there a way to reverse the canceled PO to open it up again so that the receipts can be reversed?

Thanks

Carol