I've stayed out of this but am now getting concerned for some very good friends at BA
Of course BA could always accept the idea subject to a joint ballot of all cabin crew to see if they accept it.
Other industries do it, Unite does it (in fact one of Unite's fulltime officials has been involved with doing this in an industry he previously covered as an area secretary) and of course it is the democratic thing to do, so really the union would be foolish to refuse
By the time that had been done the clock would have run out on the possibility of a srike and of course if staff said NO that would leave Unite in the cold!