Supplier credit note and release of original invoice

Hello,

We are using S/4HANA public cloud and looking for a best practice for processing supplier credit notes.

Scenario:

• We receive a supplier invoice.
  Invoice is posted with payment block. Workflow for blocked invoices is started.
• Approver will not release the invoice, but requested a credit note.
• Credit note has been received, no workflow is available.
  Credit note is posted without payment block.
• Approver didn't get a message from the system that the credit note for the invoice has been received and posted.

Question: what is the best way to inform the approver that the credit note has been received and the invoice can be released for payment?

Best Regards,

Henk Hoogerbrug