How to add an action for the Buyer supervisor in Requisition approval?

Hi all,

There is a requirement for the requisition approval as below. Can you please suggest how to mimic it?

Once the Requisition is submitted it should go to the Assigned buyer/Buyer on the requisition> Buyer's supervisor.

i.e; Buyer> Buyer's supervisor

Customer wants, Buyers need to review and approve the requisitions before converting the PO. We can see the Assigned buyer option in the single approver Routing but couldn't move forward for the supervisor.

Please suggest !!

I really appreciate any help you can provide.