Synchronizing events for dynamic actors

What is the best way to synchronize event triggers across dynamically spawned actors?
The only way I see how to do this at all is to have a Manager Actor keep track of all the dynamically spawned actors it is responsible for and use those actor references to generate (near) simultaneous events. With C++, those dynamic actors can obtain a pointer back to the manager to notify it that a synchronous event should occur.
What other methods can be used to obtain this functionality? Interfaces? Is there a more nuanced approach to the method I outlined?

Can you give an example of “Synchronizing events for dynamic actors” - e.g. example of what you are trying to accomplish

Imagine a randomly generated level scattered with bombs (each bomb is its own instance). Your player has a switch to detonate all the bombs at the same time. How would you get all of those bombs to blow up at the same time?