Two accounts, two people, one real ID?

My mother recently merged my son's account with her account into one battle.net account because she panicked when the date was looming and I hadn't bothered to set him up his own. Now my son (who is sixteen) is being identified as his grandma to all of her friends. This is slightly mortifying for him and I'd REALLY like to separate their real id. Is the system set up to allow different accounts on the same battle.net to have different real id's? or do I have to go to the hassle of separating their accounts onto two distinct battle.net accounts now?

All and all, I'm not a huge fan of the way some of the real id was implemented. It seems to be REALLY low on features to control it, only rich in features that are "fun".