Hi everyone! I'm having a dilemma because the misbehaver in question is my niece. If it were a friend of my daughter's, the friendship would be over. Please let me know your thoughts. DD is 7, with a 150+ on the WPPPSI test and possibly inattentive-type ADHD (or just plain underchallenged and bored). The problem is that she has a cousin the same age who comes & stays with us for a week at a time, along with my sis and her older daughter. Over the course of one day's time, both my husband and I heard the niece lie to DD several times. We intervened, told her lying is unacceptable in our house, etc. and yet it continues. If DD and niece are playing together (and niece thinks no one is around) and DD asks niece a question, niece will just look at DD and not answer. She'll do this 4, 5, 6 times until DD gets mad and cries. Also, if niece is looking at or reading something, she'll make all kinds of exclamations about it and then when DD says "May I see?", niece will hide whatever she's looking at so DD can't see it. When DD is doing her homework or reading a book, niece will constantly pester her. If I separate them, as soon as niece thinks I leave the room, she'll go right back over and pester. And so on. It all sounds so petty, and I've let it slide. These things happen every single time and have been happening for the past 4 years. My sis does nothing but excuse it, blame my daughter for being too sensitive, etc. It's almost like niece goes out of her way to make DD mad or sad. Where the gifted stuff comes in is because DD has a HUGE sense of justice, fairness and empathy. So when I ask her why she doesn't tell me when niece does X behavior, DD says that she's trying to help her cousin, and tell her not to do it, etc. DD has taken on full responsibility for her cousin's actions, and lets this all continue until she blows up in a crying fit, rather than come to me and ask for help. (Other times when she feels herself getting very upset, she'll come and ask me to help her belly breathe, etc. This person is the only person that DD seems to have no defenses with).
SORRY SO LONG!! but what I want to do is not allow niece to visit anymore, because she is so upsetting to DD. Do I have to let someone be in my house who lies and breaks our rules and freaks out DD just because that someone is a relative?? And do I have the "right" to think my sis is a weenie because she blames everything on my daughter, says I baby her, she's too sensitive, etc. I am only talking about incidents that my husband or I have directly witnessed, so it isn't a "she said, she said" situation.
Thanks for any thoughts on this. DD asked me if this is bullying and I said no but the pediatrician said it is, and it's particularly dangerous for DD because she wants to fix it, instead of removing herself from the situation.

PS DD goes to public school, is in Brownies, Sunday school, two dance classes, has regular playdates with 3-4 different friends, and no one has EVER complained about her behavior. Niece on the other hand has never been on a playdate, so when I try to talk to my mom about these lies & things, mom will say "but everyone at church (or school) thinks niece is so wonderful", like I don't know what the heck I'm talking about??!