Ok I understand it involves a lot of considerations. And that snapshots are just supposed to be… snapshots. I use them sometimes as forks, for example when I work on a project for two (or more) different purposes (long version-short version, different timings and treatments…).
In this particular case, I had to load and continue to work on a quite old version of a complex project, because I destroyed the edition of hundreds of regions resizing them all when I wanted to resize just one (because all after playhead was selected), and noticed long time after (after more than the 20 actions in undo-redo memory, which number I increased considerably after that…).
So I needed to import the new material from that broken session to the older.
I finally bounced them. I know where the soundfiles are recorded in Ardour, but maybe for a new user it may not be very obvious to search in this long path (session dir → interchange → sessionName → audiofiles, and search among a lot of …%L %R files). The advantage on export is there is no need to “copy file in session” and thus use double of the filesize on the drive.
Still, it could be a good idea to have a shared list of sources.
Thank you for your help!