Should I put my parents in their place, or just stop seeing them?

My parents treat my kids like crap, and coddle my brothers kids. They have never respected me, and now they are starting on my 5 year old, always telling her to stop doing things, when she's 1 of 3 kids doing it. They give favoritsm to my learning disabled nephew, make sure that no one does anything to upset him, and then come down on my daughter. My dad also went and got my nephew an old hockey set from the neighbours with my brother, and was trying to be all hush hush about it so we didn't know anything about it. Should I say something to my parents(wouldn't be the first time)and upset them so they won't talk to me for a month, or just make up excuses not to be involved in family events for a while?