Locking critical curves and edges

I’ve a recurring issue with the orthogonal soundness of curves used for construction, or rather, certain edges of surfaces created with a curve end up out of alignment or untrue after a series of matching surface operations.

When I’ve accomplished a smooth transitional corner I end up with an annoying chore when it comes to finishing off the solid it’s supposed to be part of.

What I’m wondering if there’s a means to lock or ‘insist’ that certain surface borders remain exactly where the
construction curves are placed.

Attached is a typical problem. Trying to create a solid to ultimately boolean, is fraught with failures.

ArgoFlex7.3dm.zip (926.9 KB)

The first images show the positive intersection of the curves meant to make surfaces with, as well as making sure all are planar.

I end up with a problem not only creating simple planar surfaces, but getting a complete surface connectionsl

It is not possible to force surfaces to always remain exactly on construction curves exactly for all commands and actions. The reason the surfaces are moving is because of the way you are creating and/or modifying the surfaces.

What sequence of commands/actions did you use to create the surface with the problem in your example?