VK,
I can't see it!
Notlangley,
Don't know if you can join without joining Bassa or Amicus.
The Unite website does let you but they may well allocate you into one of those branches, if you did join.
Without trying I could not tell you and I would expect all of us that left, would not have wanted to rejoin Unite, not just yet anyway. Most of us have signed the individual offer and that is only possible if you are not a member of Unite.
Not much help I am afraid.