Adding Adhoc Approver Before Current Approver in Requisition Cycle

The customer wants to modify the requisition approval process to allow the current approver to add an ad hoc approver before themselves in the approval cycle. Currently, the "Add Assignee" function only permits adding an approver after the current approver (if they are not the last approver). They need the ability for the approval notification to be routed to the newly added approver first and then return to the original approver for final approval.