I wouldn't let them switch. Odds are that one of them is bound to regret it and want to switch back. Then what would you do? I think it is bound to create bad feelings towards AG dolls and towards each other. If your kids are anything like mine, then they have sentimental feelings towards their own doll even if they may think they want their sister's doll. Maybe you can plan in the future to get them each a doll of today that looks like them and that could become a best friend to the doll they already have.