This has been very thoroughly discussed on these boards. I'm not sure how far along your team is, but if it's not too far you should seriously consider just replacing your brother's old account with a new account of your own. If you have a REALLY good story you MIGHT be able to get the name on the other account changed. But just telling them "oh my brother stopped playing and I took over his account, please change it to my name" won't cut it. Failing to take action to resolve this will almost inevitably result in the banning of your accounts, and not just the one not in your name! If your team is pretty low level, it's no big deal to replace one. Even if they're high level, with the RAF bonus you should be able to get a replacement up to speed pretty quick.