Remaining grid internal Curves / Surfaces

[user23]

I have a series of overlapping grids that I want to be able to find the resulting left over space/surface/curve (marked in red) help much appreciated!

220907_overlapping grids.gh (20.9 KB)

[HS_Kim]

220907_overlapping grids_re.gh (20.8 KB)

[user23]

Thank You!!!