Wow, that's much weirdness. I've only done 2-man BHs so far and have noticed only the following:
If Person A has a contribution of 100xp in the Brotherhood window, then Person B at login will get
50 xp, not 100. I concluded from this that "contribution" means total xp earned, which is then divided among the BH members.
However, I have not yet been able to play both members of a BH at the same time, which may complicate matters. I'll try and do that a bit later today, once the other computer in the room is free.
