Drag and Drop that needs to use multiple layers

I am building a tool for a student to do a bubble diagram to plan the organization of a multi-floor building. Since the organization of the second and third floors need to fit within the profile of the first floor I need the student to see the objects they arranged for the first floor.

My thought was to use layers. The first floor would be built on the base layer which could be visible when they go to either the third or second floor layers. Great.

Here's the problem. I need them to have different draggable objects on the second and third floor layers so they can build out those floors, but this does not seem to be possible.

My only other thought was if there is a way to use javascript to capture in image of the first floor slide, as they have arranged it, and set it to the background of a new slide that they can then use to do their second and third floor. The image would also need to refresh if they went back and changed something on the first floor slide.