Mass Entity - Post spawn manipulation of entities

Hello,

What would be the proper way to pass information from a world subsystem or a level actor to a Mass processor in C++ to make the entities behave in a different way through input?

For example, I have an actor that starts a timer and increments a counter after some time passed up to a limit. I would like to have the active entities do something once the counter is incremented by the actor.

I have a Mass world subsystem that can spawn any number of entities at a given location and a processor that makes them change location over time.

Ultimately, I need to know how many active entities each group have in order to assign a random entity as a target for each entity in a processor.