the steps one needs to make after inserting a point in the "polygon hull line" in order to get (almost) the same curve back you had before inserting a new point seem to be the same every time.
I have made a lot of images and hope they make sense. The last one makes me think the points can also be calculated. (The red point is the position where the new point was inserted in the original curve's hull line and the locked, grey original curves are never hidden.)
