I kinda agree with the mom...she is old enough to decide for herself. As step mom I would stay way out of it! I think at the age of 10 its normal for her to be mean to her sibling, I dont think its right and shouldnt be condoned or excused, and as for the lying, I really think its the age....10 year olds always feel like they are the victm and every one is being unfair to them, even if they are little meanies! It sounds like normal pre-pre-teen things to me.