How do you amend who receives a 'requires receipt confirmation' email?

Summary:

A user is receiving a procurement 'requires receipt confirmation' email for a purchase order where they have to mark it as received in full, receive up to the invoiced amount or didn't receive however the user receiving this escalation is no longer the line manager for the person who had raised it. I have reviewed all the available parts in Oracle Fusion that may have had them down as their line manager previously but nothing is still showing that.

I have highlighted the previous line manager that is receiving the escalation that shouldn't be in the bottom screenshot, and the buyer in green.