Stay classy, Bella. Don't get semi-slutty like your oldest sister in a few years (though she's not nearly as attractive in the first place :P).
I'm going to have to disagree with you. If all three of the Thorne sisters want to be as naked in public as they are legally allowed to, by all means, let them do so. All the more chances to see their naked navels. Besides, they are too sexual as it were, no amount of clothing can conceal it.