How to Stop PR Approval hierachy when the person in the hierarchy is 'inactive'

Dears,

In PR Approval hierarchy,

The Approval sequence goes from A->B->C->D

when the User account 'C' is Inactive status the PR Approval goes from A to B skips C and moves to D.

But in the same case for PO Approval the hierachy stops at C and notifies the A and B that no approver was found and the PO header status change from 'inprocess' to docment previous status (incomplete / Requires Reapproval). so that we can resumbit the PO

i need this exact process for my PR as well.

Thanks in Advance.