This is probably one of the best, most informative, interesting threads I have read in this part of PPRuNe!
I notice that bmi publish there load factors and pax figures each month en-masse. They don't break down mainlne, regional and baby.
As a guess I would imagine that baby's load factors are the highest, so by lumping all three divisions together you end up with a figure that is reportable via press release.
If they were listed separately ............?
As soon as baby get their own AOC I think they would be better off out of bmi mummy.