Like I mentioned earlier you can have an over-arching manager in the form of a blueprint library or module with static functions (requires c++). You can also have an actor passed by ref but it’s not as easy to use.
It can be detached from any actor and shared among them (like Game Instance, Game Mode). You could then call it’s functions from anywhere in the game passing in inputs for calculations or reference actors if they need to have their variables modified and returned.