Need to add an approver in PO Requisition Workflow

Hi,

I need to add an approver in the PO requisition Approval workflow. Currently the Approval hierarchy includes HR hierarchy. Business wants to add Approver from Procurement team just after the first level Supervisor approves the notification. At this time aaproval notification should go to Procurement rather than the normal HR hierarchy. We can add approvers at the end of approval hierarchy but in this case we want to add in the middle of hierarchy. Any idea how to do it.

Thanks