Thesis Help - Cutting Holes

Hello,

I am working on thesis and I have been struggling trying to figure out how to cut a hole out a parametric wall.  I have attached the GH file, the areas controlling the parameter and surfaces which should be subtracted from each other are in purple groups. 

I cannot seem to get the window to be subtracted from the wall when they intersect but not when they do not (the cull command deletes the wall because it is the only indexed item). 

I have been trying to create sort of IF...THEN statements but I cannot seem to get it working.  Help would be greatly appreciated so I can start writing my thesis.  This is the last piece to the puzzle.

Thank you!

Reinhardt