Problem with set materials

At first, sorry for my english, im italian. i try to explain best as i can

The objective: Is a spaceship game, game have several ship (two for now). Inside the ship i have a main screen, i want this screen show what is outside using a camera.

Now when game notice that a player want to join an empty ship, he create the ship (with a map instance called “nave”) and spawn the player character

And give to each ship a different number.

Now, when map is loaded i want to change the material of the main screen into the rendermaterial of the camera of the corrispondent ship (so main screen of ship one have camera of ship one, and same for ship two).

Im trying to do this with that blueprint

Well the problem is simple, if i set the materials at start they work both, but the blueprint dont change material accordling. (camere is an array with the material from the cameras)

Any suggestion? Can i choose the material before level is loaded?

thanks a lot for any useful answer