Hi Rudl, so maybe one feasible manual drawing strategy would be to get some lines drawn in at the 4th quad corner coming off of it like a surface normal, then you can draw in a plane through 3 points and use Construct > Curve > Isect to intersect it with that line, that will then give you the adjusted 4th planar point for one quad, then repeat this across the surface.

I'll see if I can give you an illustration of this way.

- Michael