Is there are way to update a piece so that it has the same objects (e.g. nodes A, B, and C) but those objects have been moved (e.g. from a measurement change) without having the recreate the piece by selecting all the objects in the path again? I’d like the maintain the same nodes, seam allowance, notes, etc.
Seamly2D is a parametric drafting program, so what I think you’re describing is exactly what it does. So you can switch clients’ measurement files to get properly sized patterns without any additional work. The Layout mode needs re-rendered, but the Piece mode adapts to the current measurements automatically. (Unless you accidentally expect Seamly to be psychic, & aren’t using the measurements files.)
If you wanted the opposite effect, so that the traced size was persistent in-program, then you’d have to re-draft from scratch for each size.
As @Pneumarian has pointed out Seamly is parametric in that in order to automatically adjust sizes, a pattern has to use the measurments in the formulas. If I my ask how are you drafting patterns? Are you using one of the many patern drafting systems? If I know how you’re drafting paaterms I may be able to offer more specific suggestions.