I have a non-planar surface with multiple holes, and these holes were offset on the surface shown in the green color. I want to split the surface using these green curves and extract a large surface that will be left after the splitting operation.
you can use Surface Split to do that
you will get a list of split pieces, after which I think -given this particular shape you are dealing with- a good way to isolate the bigger Fragment might be to sort them by surface Area, and pick the largest one
I already tried this but was not able to extract that larger surface.
please post your GH file with internalized geometries
you might want to include only the part of the file where that particular issue is taking place, in the end just the surface and the 4 cutting curves are needed 
Please find the GH file. Also, a step file will be used to set one beep at the start.
non_planer_split.gh (9.1 KB)
Import the step file in the rhino.
Non-Planer 01 v0.step (214.3 KB)
the problem is having the curves organized in separate branches:
that means that each curve is splitting the original surface separately, and the result is like:
a list with the whole surface divided in two by just the first curve alone, then a second list with the whole surface split in two by just the second curve alone… and so on, for each curve
flatten the curves and it works:
Thank You so much.
