Adaptive Component by three points

I am trying to place an adaptive component family using 3 points created from a .SAT curves.
Basically I took the end points of the inserted curves, then offset-ed them, but I have a problem that the 3 points don’t follow the original end point’s.

Is there any trick to “transform” or “rotate” those points to be perpendicular on the original end points?
The goal is to have something like the one in this screenshot:
Thanks