BIG-IP DNS - application dependencies

Hi I have a question related to BIG-IP DNS and how to establish application dependency. Example is like this. A Dual DC solution with GTM in each DC. Two applications, we can call them app1 and app2. Wide-ip-app1 points to dc1-app1-pool and dc2-app1-pool. The same setup is for app2.

 

What I would like to achieve now is that if either dc1-app1-pool or dc1-app2-pool is down, both pools should be treated as down and DNS response to client should point to DC2 instead. I have been thinking of two different possible scenarios. 1 - in pool health check monitor also check availablility of the dependent pool. 2 - Try to achieve something using iRules on the Wide ip's.

 

My first attempt was to use distributed application functionality but there will be more paralell apps in each DC and customer don't want to fail over all apps to DC2 if one of the apps are down.

 

Some advice on this topic would be much apprciated.