Flatten quilt - two merged surface

Is this that same yoke that I replied to earlier?

Honestly, I haven't played with flattening quilts at all.  Never needed to, so I've never looked at it.  BUT, and I'm sure those far more expert in it than I will chime in (hopefully), it stands to reason that a quilt that cannot be "developed" (e.g. a "ruled surface), probably would not be able to be flattened because it would involve stretching of the material.  Toroids (your quilt), spheres, etc., are not "ruled" surfaces.

Why would you want to flatten this?  Is this being made of carbon fiber and you need a flat pattern?

Best of luck in any case!

When I've had to do this type of thing, with surfaces that have odd behavior at a common internal edge, I've made a flattened quilt of each of the surfaces individually, then used an assembly to position them, "joined" at the interface edge, and created a new flat surface via the assembly. It's not a nice way to do this, but it gets the job done.

Also, remember if you're doing this to later form something into the shape you start with, the quilt should be offset to the middle of the thickness of the material you are going to be forming, not on the exterior surface of the final product.