A tam nie ma gdzieś w transformie snap to grid?
I had a hard time figuring out where Autodesk put the snap to vertex in the unwrap editor myself, but found it after a while. If you want a vertex to snap to another, you can only use the "transform" tool in the upper left corner of the editor. That, in conjuction to the snap to grid button to the bottom right should make your vertices snap :) I don`t know why Autodesk won`t let me snap with the "freeform mode" tool though..