Cattivo,
I think different contracts have existed in the past and there are anomalies that exist for a number of reasons. If you ever see an MSL with DoJs on it, you'll see what I mean. It is no big deal, and all above board. It is possible that bmi pilots may end up at the bottom of the MSL, way above my pay grade, but their DoJ will remain their bmi, or indeed BMED DoJ.
The point about seniority numbers is that your actual number isn't terribly relevant. What counts is where you are relative to other people, how quickly that position changes and what it actually gives you.
For instance, would you rather be 50 out of 100, or 80 out of 200?
What about if the role of preference for you was at 30 in both airlines? Or you moved up 10 places a year in one and only 2 in the other? Then which would you choose? Your actual number means very little.
If a solution was found that increased your number by 50 places (ie
Downwards), but left you in the same, or higher, position as a percentage of the whole and moved you a few years closer to your goal, wouldn't that be a good thing? Where would it sit on the 'disadvantage' test?
Merging bmi's operation into BA, adjusting fleet profile and route network will adjust all the variables. There is so much more to look at than 'what number am I?"
Stagnation is a terrible situation for seniority based systems, with the retirement changes and lack of expansion it has affected several airlines badly. This merger, combined with the impending easing of the retirement bubble, should ease both of those stagnators.