Brothers are a whole different ball game. Ive had school aged brothers twice before and its just a matter of them learning that rules were different here. Not sure how old these boys are but in any case, chances are they fight at home, rough house that sort of thing and its not dealt with. How you handle it will depend on their age but consistency and a firm explanation of the rules and consequences for not following the rules. I think you need to give it more time but definately ask mom how they get along at home.