Ah, so you need some fundamentals of Blueprint Communication (there’s a good course on it in lear-Online Courses)
To talk to one Blueprint from another, you need a reference to it. The blue pin you can drag out to read/set its variables or call its events.
Say, this event which sets the color of a carried box (held by the character) based on the integer color being used to represent colors (0=Black, 1=Red, 2=Blue)
If you need to reach this in every bp_character in the game world, you can loop through all of them by getting all actors of their class.
But maybe you just need the actor that bumped into this object’s collision.
And of course, the blueprints you register with the project can be called with their class type and the project’s reference.
Eg, if you pick a game mode in Maps and Modes…
Or if you pick a game Instance there.
