Grasshopper - Randomly populating a rectangular grid with curves, one which occupies 1 rectangle but one occupies 2 rectangles

Hello everybody, I would like to populate a rectangular grid randomly with different types of arches. I have an arche that occupies one rectangle (approx 3x3) and another arche that occupies two rectangle of that same grid (so 3x6).
I managed to create the two grids, (one for each type of arch) but i would like to combine the two grids and generate random patterns keeping only some of the arches…
I know this is not very clear but here are two screenshots showing the two grids and an example of a randomly generate grid I would like to have.

Have a look at the attached def. (13.1 KB)

Thank you very much for your help I’ll study your proposition!

Check this as well. (11.9 KB)

I took a shortcut using an Arc instead of your curve but thought the tricky part was getting the pattern of rectangles. You can map anything you want into them. (21.0 KB)