Forming a shell structure from curves

Hello,

I'm trying to form a shell structure from 4 base curves. I want to be able to change the distance between curve points and the shape on the curve using grasshopper.  I was unsure how to do it so modeled the curves in rhino then set those curves into the curve function in grasshopper. Also, I found the 3 point arc which can connect 3 of the curves together to form a surface, but how do I connect 4? 

Any feedback or advice is appreciated!

Thanks