Creating AME rules in iProcurement

Hi Team,

I need your guidance for defining the AME rules in the iProcurement, actually following is my requirement and I built it 80% for remaining I need your help

>  My approval rules is working currently as, I created it for 'item' based for e.g. if 'X' is an item then approver should be A and B (order 1 and Order 2 resp.). It is working currently, however my complete requirement is if request is approved by 'A' then it should go to 'B' and after 'B' did his job then it should again go to 'A' and once A 'approved' / 'reject' in that way my request should complete finally. (in this A will be the final approver)