Thanks Michael,
a good idea with the diagonal lines for the example (rectangle).

The problem is that I'm looking for a solution that is also working for closed curves that were designed with a Freeform line. Here the the line behind the outline needs to be a child of the outline. Next line needs to be a child of the first child, etc.

I had in mind that such a function was/is existing in MoI or as script from Max Smirnov.

But thanks a lot for your trying to find a solution,

Joerg