You move all your policies that reference indexes (EDM/IDM etc) into a policy group targeting only a sub-set of your detection servers. However you notice that the indexes are still replicating to all the detection servers.
Release : 15.x
Component : EDM/IDM indexes
This behavior is as designed. There is currently no way to restrict index replication between detection servers. Each index is replicated to all detection servers.
A feature request has been created to add this capability into a future version of the product.