How to assign Evensystem to a specific canvas to work.

[Note: I found multi EvenSystem is not supported by Unity].

Hello, I am using 2 canvas in a scene. one is always on screen & another one is popup at runtime.

While popup canvas appear then it is not working because of EvenSystem is already assigned to previous one. I found a solution like, if i set a canvas to "Canvas1.enable = false;" then popup canvas is working properly & Canvas1 disappear.

But my problem is that, I don't want to Canvas1 disappear. Just want to assign EvenSystem to Canvas2 without disappearing Canvas1 by "Canvas1.enable = false;"