AR Customer refund invoice approval in AP

As per existing SR Note of Oracle it is confirmed that we cannot have approval rules for Customer Refund in AR

There was business requirement asking whether we can have approval setup for these invoices in AP.

We tried creating a Approval Rules in AP with combination of Invoice Type as Payment Request and Source as Receivables but same is failing mentioning Receivables source is not mentioned in Lookup.

If anyone has implemented this in any of your earlier project, please let me know.