Could be possible for the game to automatically to set up a shared OneDrive folder that is simply shared by the players in the group, then hosted by the first person who loads into the world. If and when new players come in and out, copies of the save can show up on their OneDrive also. It is possible to do. Worlds are already numbered, it would require the use of some document syncing API code already used by Microsoft Teams, but certainly doable.