Maybe a selector on the computer that says which version you can choose and even glitchs from those versions work but everything u get from older versions is not saved and is only saved from the older version
IDEA FROM @runic hollow
And you start with the items you had in that version, if you have nothing or haven't played that version, you would have nothing when you join the version.
Idea from Dog👍 (ME!)
Also make it so u get complete kicked into the og loading screen to make it so it's very hard to glitch og items to newer versions