Thanks for getting in touch! I'm not sure it would be possible to modify a previous release in this way. Theoretically it may be, but it would require modifying a release snapshot to create a release from. It would at least take quite a bit of work if it is in fact possible, and wouldn't be the approach we'd recommend.
If v2 is different enough and need them isolated, I would definitely suggest creating a separate project for v2. If the process only has small differences, a good solution could be our channels feature. You could define the same lifecycle for each channel to promote it through the same environments, but this would give you the ability to scope different steps to an individual channel to control which ones run when. You can also scope variables to channels.