Sorry about this below Z=0, You are right, I was moving the spline and surface UP, without the RC object itself.... so it seams that something strange was happening when the surface was above the RC object. By the way, because rokas mentioned that these are not limitations , so i want to make it clear that i wrote about what I noticed not as a criticism but for information for other users that might use it
ofcourse i'm very thankful for Your help and quick solution !
The most important thing is that it works and RC is even more powerful now !
by thw way I like Your idea of stacking those support segments instead of scaling them, I will try to implement this also to my platform.