How to determine which priority group is active with irule

Actually I have 6 members in a group, Member A, B, C with higher priority and member D, E, F with lower priority. Least available members configured to 2

 

 

Now for particular bunch of source IP, I want the traffic to stick to one member of a pool. So I can make an irule with match class and select member as A.

 

if A is down go to B and if B is down go to C.

 

 

But the issue here is, let's say A and B is down, so priority group will fail over to DEF. But above irule will still send traffic to C which is creates a discrepancy as my other traffic is flowing through D, E, F.

 

 

So before selecting a pool member I need to know which priority group is active A,B, C or D,E,F and then send traffic accordingly.