Hi Patrick,
Your brother can do anything you can do in wikitree if he has become a family member and has signed the honor code. (I didn't check that.) The only thing he can't do is work on profiles that are not open (not having a green unlocked padlock). If there are profiles that are not open, you can click the Privacy tab for each profile and add your brother to the trusted list. Then he can work on those profiles too.
