Boundary problem

Hello,

I am new here but I really need some help with a task.  I just started using Grasshopper a few months ago so I apologize in advance for any misunderstandings (and my bad english) :)

My problem is that I have a plane which should be a slab in further development and this slab has 2 openings (rectangles). These openings must be moveable but just on the slab, so they must not go further than the border line of the slab. The slab must be able to change its dimensions (that is what I already have) so the movement area of the openings should be changeable. How can I do that the openings stay inside of the border line?

The second thing is that the openings also must not intersect or touch each other. Is there any possibility to do that?

I was trying so many things but none of these worked properly and I hope someone from the community can help me. 

For better understanding of what I was talking about I made a little sketch.