INTELLIGENT POLICIES CONTROL NUMBER OF VM

Hello,

I am starting with VIP and I will like to know if someone know a simple way to control the number of virtual machines that are in a VIP.

I don't want to back up more than 80 virtual machines in each policy, but I don't know how can I control this.

At first I though to add a "counter" in "Annotations" to do this, but I cannot do this because of some performances.

Has somebody already did this or can somebody give me a clue? 

Thanks!