How to know when a co-routine that is being implemented by multiple objects ended?

In a project that I am building in Unity I have a Master Class (LevelManager) who does:

EventManager.TriggerEvent ("Fade");

The multiple objects that listen to the event trigger a co-routine for 1 second to “disappear” (they lower their alpha channel of color to 0).

What is the best way for the master who fired the Trigger to know that the objects have already disappeared?

Any way to solve it will be very useful !!

Thank you

For now I have it solved in the following way: At the end of the fade co-routine the objects call :

EventManager.TriggerEvent("FadeEnd");

and the LevelManager as soon as it does an :

EventManager.StopListen ("FadeEnd");

so as not to execute the method multiple times and continue with the animation … But I’m sure there are more correct ways to do it … Any suggestions?