We appreciate you for coming back, Charlotte2771.

If the transaction is already reconciled, you can still delete and recreate the check to show it as a Bill Payment Check. Then, do a mini reconciliation or special reconciliation to re-reconcile the transaction.

You can follow the steps and details in the Reconcile previously deleted and re-entered checking or credit card transactions article. Then, choose Method 1 or Method 2 that is appropriate in your situation.

If you don't want to delete the reconciled check, you can re-open it. Then, add a description in the Memo field that it is a Bill Payment one.

Please reply to this thread if you need anything else with managing vendor transactions in QuickBooks. I'm here to help.