there is no legal minefield it is all very easy.
If a voluntary agreement is in place between BASSA and BA or Unite and BA then the ONLY people who can terminate that agreement are the signaturies.
A voluntary agreement is not covered as far as derecognition is concerned and therefore membership numbers/level of support is totally irrelevant.
If however there is a statutory agreement in place (which I know there isn't) then one, as in the bargaining group, could force a derecognition ballot.
It is this that the new cabin crew group have failed to grasp. So unless BA or Unite terminate the agreement it is status quo for a long time to come.
On that basis perhaps a more positive approach should be adopted by BA management as far as discussions with BASSA are concerned. What do you think Diplome?