When you see your niece being unkind to your daughter, you need to step in and provide some respectful, quiet guidance about the way "we treat each other in this house." Never show a shred of anger because this little girl needs to learn that she can misbehave and an adult will guide her with sensitivity and respect. She needs to learn an alternative to abusive communcation and discipline. You're going to be the teacher. You'll have to also set your own daughter straight: "this is not the way the 'Jones family (insert your own last name!) behaves." You're trying to build up a sense of family and boundaries that will last your daughter a lifetime. By teaching your niece, you are providing what will be a memorable "safe place" and you can have a lasting impact on her as well. Both children need to receive negative consequences for aggressive behavior but those consequences need to be non-aggressive - i.e. a time out, a loss of privileges etc. See Raise Your Kids without Raising Your Voice for details on how to quietly, kindly, yet firmly discipline children (see The Two Times Rule).   Sarah Chana

Give your brother-in-law a copy of Tactical Guide for Dads in the Field - the men's mini-version of Raise Your Kids without Raising Your Voice. Then, to make sure he reads it, ask him about it in a couple of weeks and try to talk about it with him. Maybe you can influence him.

Don't let either of t he kids be abusive. They need to be disciplined. But don't yell at them or get all worked up because that will only make their behavior worse. They're already copying an abusive man.