How to pass information to a Blueprint Child from SpawnActor

I am making a random maze with the common random maze generator, but I am including doors to be locked with keys. The idea is to have a chance of spawning a key in a room, and then that key will open a door somewhere down the maze. I want to link a given randomly spawned key to a randomly spawned door by indexing them both to the index of the room that the door is attached to. I am spawning the door with the SpawnActor function as well as the Key, but I’m not sure how to pass the “current room” index to the actor being spawned. Is there a simple way to do this or any other methods of doing what I want? Thanks in advance!
Just as a visual of what I have and what I want, here are some pictures.
What I have:

Something like what I want: