Creating a surface for a non planar closed curve?

Hi there!

I’m just trying to add a surface to the curve highlighted in the image. I just want it flat across and was wondering if there’s a simple way to do this? I know there’s a way to do it before making the other surfaces and building off that but was curious if there’s a way at this point?

Could you build a manageable surface and manipulate the control points to get it close to the curve. Then possibly extend the closest surface to it, through that surface that was just made.—-Mark

How simple depends on the details of the curve. Post a .3dm file with the curve.