How about this:
People sign up at BALD for the battles reporting, and they get to pick which thread their reported battles are counted from. We then take the list and search for people who have signed up, and determine the records that they have accumulated from their reports on whatever battle reporting thread they chose.
Either way, if they report battles often, they'll count at AA towards rank-ups (to a certain point), and they'll count towards the records kept at BALD as well, along with the benefits given there too.