Hello and thanks everyone who can helps
How move vertex along spline in edit spline object and don't change contour of spline? meybe something similar to edit poly objects - moving vertex constraints edge mode?
Or even much better put distance between vertex but it mustn't change spline's contour
and example what really needed:
P.S. And I know this script http://www.scriptspot.com/3ds-max/scripts/spline-toolbox
have some function - Constrain Spl. Verts, but it doesn't work good enough