map line geom to a 3d curve ?

Hello again,

I would like to know if there exists some way to 'map' all the operations I have made to a volume on a linear axe into a spline axe.

Let me explain:

If I divide a line unevenly, how do I map all this segments to a spline of different length without passing a point list and placing them all over the curve again.

Also more triky is to pass, for example, circles along a line to circles along a spline, because the normal plane would change at every point. How can I correlate the points base planes from one linear axe to a 3d curve axe? (base change...?)

I hope this makes sense... Ideas? Keywords that should narrow my search?

I am working with C# nodes.

Thanks in advance!

Miguel.