The dynamic area in Galapagos

Hi all…
I am a beginner in grasshopper and I want to use Galapagos in my thesis.
I plan to generate a floor plan and change only the area of spaces with standard dimension ( without changing the position of all rooms )
Is it possible to do that in Galapagos to find the best area for all room with fixed boundary and how I can start ??

Any thoughts would be appreciated …

You need kangaroo to do this, more than Galapagos