Cool. I'm planning to do a DS9 marathon soon-ish, so I can revive my memory of all the little details I've forgotten.
I checked out the MU and regular Jadzia and Ezri profiles on Memory Alpha (ST wiki) and MU Ezri definitely wasn't joined. The info on MU Jadzia was more vague. They don't list her as joined or unjoined, while other Trills are specified, but she still is listed with the name Jadzia Dax, while MU Ezri is listed with her original name.