Hi Pilou, also of course if you wish to make adjustments, it is easier to preserve the original curves, either hidden or saved to a different file or something. That then eliminates the need to extract them to recreate them.

Also it's good to know how the original was created, like is it a shell, is it an extrusion with a piece cut off of it, and so forth...

All that information from the original creation makes it easier to reconstruct the model later.

- Michael