Finding angle and number of revolutions on spiral curve

Oh spirals are not easy :slight_smile:

Imagine I’v made spiral curve. I then split it at specific level (it should be adjustable) it gives me a point.
I now building a second spiral curve which should finish at the point I got from splitting first spiral.

So what I did, I subdivided lower portion of the first curve and found and angle between first two points it gave me a total angle which I used to create second spiral.

The problem is I don’t have control over how many revolutions I have (in second spiral) and if I change the height of spitting it all goes to nothing… (50.2 KB)

Maybe this will help to understand it better.
You see how the bottom spiral do not match with points
Screen Recording (Rhino 7)