SRM brf N-Step approval questoin to allow more then one approver

hey guys,

I am new to brf and for my PO it is sending it to the contracting officer for approval after the buyer creates the PO. If the buyer edits the PO that is waiting for approval it is resending it to the contracting officer for approval.

I am using the standard /SAPSRM/IF_EX_WF_RESP_RESOLVER to get the agents and added my custom logic to get the contracting officer for that PO.

My question is how do i set it up so that if contracting officer is out the buyer can approve the document? Can i get step by step? Thank you.