MissM - I'm keen to avoid the all-too-frequent ganging up on supporters of one side of this dispute - but...
We want some sort of control of Mixed Fleet which BA is not willing to provide us. They are willing to 'discuss' route transfers and such with us but nothing else. Discuss means nothing
Why should you have control of MF? You, me and all the rest of our colleagues are merely salaried employees of BA, a commercial company run on behalf of the shareholders by the Board.
Historically, BA have gone beyond their statutory (and moral) duties in including our representatives in discussions and decisions taken to improve the business, and we have all reaped the benefits over the years.
However, we have no 'right' to control anything. If it is beneficial to BA to discuss things with us (and it usually is - happy, involved staff are more productive than miserable, excluded staff) then they will. If it is not beneficial from a purely commercial viewpoint, then they do not need to discuss. They are never going to 'guarantee' anything anymore - least of all control of commercial decisions to a staff group.