Hey,
I think your strategy might not be the best for the tools that Dynamo has (others may correct me)
I would create the overall surface, split it by the lines to get the sub-surfaces, then filter the sub-surfaces you want.
I don’t have exactly your example, but this is similar…
You can see that the taco shape has been created from splitting the nurbs surface by curves (I pulled lines up to split, but you don’t necessarily need to).
Hope that helps,
Mark