BASSA are the ones who can put an end to this dispute and will do so when they have received a satisfactory proposal. Not Unite. Not BA.
Unless Unite no longer agree to bankroll BASSA during the dispute which would put BASSA in a little bit of a pickle.
I feel that Unite are rueing the day that the Union rule changes removed their ability to dictate change to the sub branch. I might suggest that the fact that the branch held an unofficcial 'show of hands' to extend its tenure beyond that normally allowed without re-election might give Unite a legal loophole to enforce change.
We will see as everything is conjecture up until this point.