I just finished my organizational politics and power class for my MBA (halfway done! Woohoo!).
Anyhow, this was an incredibly powerful course for me. I read a lot of books, and a few I felt pertained to my situation with my in-laws. In fact, I believe my professor mentioned his in-laws several times as examples.
Here is some of the literature we read:
"Dinosaur Brains: Dealing with All Those Impossible People at Work"
"Getting to Yes: Negotiating Agreement Without Giving In"
"Stumbling Upon Happiness"
The books are old, but relevant. These are strictly superficial reads, but it made me think. Boundaries came up a lot A LOT. I beleive our generation has been taught to believe that boundaries are to be given out readily. "You need to train people how to treat you," was the theme of the course (aside from trying to make sure YOU yourself aren't engaging in any of the behaviors you might find obnoxious). The "training" of other people is done in the form of boundaries, and it is encouraged to be done before you even know whether people are difficult or not. If you lop "at work" off of the first title, it's a pretty handy guide (as well as a good way to validate your own feelings on occasion).
Turns out, I saw a lot of the dinosaur behavior in myself. It did give some resolutions as to how to deal with types of difficult people, and it listed tips as to how one can avoid engaging in that type of behavior themselves.
Stumbling Upon Happiness was interesting because it made me realize happiness is a state of mind not a destination. It was a little scientific with lots of anecdotal evidence, but it did help me to realize that happiness doesn't come from the situation at hand, it comes from within.
Not all of it was relevant to family situations, but it all gave me a ton of insight into my own.