SR71,
BA didn't want or need Baby pilots bmi mainline had more pilots than required So the simplistic Q?is what concessions BA would have required of the BA pilot community.
Not sure how you'd persuade BA pilots to take a pay cut in order to bring another companies pilots into the fold.
Perhaps the Q should have been asked of the bmi CC if you have bmi contracts . They negotiated with BA to keep outstations and training pilots on.
Additionally some hold poolers and City Express pilots would not have been happy.