Dispatcher called from a child actor within blueprint not working?

I am setting an elevator and i want to have only one blueprint for all the buttons, with two child blueprints (BottoneUP and BottoneDOWN)
In the pics attached you see on the right the blueprints placed in the level, on the left the same blueprints placed within the elevator blueprint.

I cannot cast to the elevator directly because i cannot set the public variable from elevator blueprint (and cannot find a way to expose child public variables in parent public variables, hence cannot set target Blueprint)

So i thought i would use dispatcher instead, but cannot manage to let the dispatch out from the blueprint. I have also tried to setup a “repeater” in the level, that would have received the dispatch from the child blueprints and then send back another dispatch meant to bind the custom event within elevator blueprint, but it didn’t work as well. Any clue about this?