>> And how did you split edges/curves at exact position
SplitHelper created with Multiiso script
http://moi3d.com/forum/index.php?webtag=MOI&msg=6841.3



Outer edge with > STRG + C > STRG + V > Join > Trim with AddTrimPoints at SplitHelper position and option keep.
Middle lines drawn with curve through points.

Result Old uv layout and new.