Fir Tree
I think that was answered in No Pushovers lengthy but informative post earlier, to quote:
Originally Posted by No pushover
When BMI integrated BMed, we were specifically and unequivocally told that it MUST be done by DOJ by BALPA HQ or else there could be a legal challenge to the seniority system. This was done and despite a number of Senior F/Os moving down the combined seniority list, even I believe they would say that they were not "disadvantaged".
So to me it would appear that Bath Road BALPA were the ones who were behind this motion. Perhaps some more posters can confirm/deny?