to keep the history intact does not always work, even when trying around with nothing else in the scene. It works most of the times but not always. I'll try to remember this the next time i run into it and send you the scene.
Here I mainly work by setting up the paths, extruding things and then hide the path and profile...

What I recognized - if I mirror the extruded model and rework the path on the original sweep it also changes the mirrored copy. If I just copy the sweep object - the copy is not changed, when changing the path spline of the original. Is this intended behaviour?
(I really like that mirrored copies are changing along, but this is not always desired, the same goes for that I'd like to have normal copies change when the original is manipulated sometimes...)


Edit:
All works fine here. I was probably referring to something else that was bugging me: When I setup a pipe roughly in outlines, use it and afterwards want to add roundings - changing the guide / path spline doesn't affect the sweeped pipe (probably because of adding points to the spline?)

and in that regard: is there a way that once setup roundings on a spline can be deleted without redrawing the spline? f.e. moving the 2 guide points to a distance of 0,0,0 merges them to 1 point that has no more bezier function? Or can I join point that share 1 coordinate? Is there a possibility to switch the two points of rounded corners to behave as corner points?

working with it lots of questions pop up that might make working with it easier... nethertheless I LOVE MoI!
(I prefer to use it here over the CAD Program I usually use - Vectorworks. The import via .sat works great btw so I model in MoI and import the final product... :) )