Is your object created with extrusions? I have this switched off.
I have attached the two volumes. It doesn’t work for an open volume too and I can repeat it every time. no ME.3dm (217.3 KB)
Move Edges only works vertically.
I need it working for Grasshopper.
If it was Rhino only, I would adjust the curve and then form a volume.
Actually, my problem was ‘no face merging after splitting the volume and creating the fill’. See image 2.
I started investigating and got to the basic of this thread.
I’m not sure which image this is referring to.
As for Grasshopper, to get around the creasesplitting issue, you could probably, in Grasshopper, explode the curve, extrude the segments, and then join the surfaces.