I was surprised how often this theme pops up...It came up when we were discussing Ordinary People (in the Donald Sutherland review post). Take home some CPL dvds and revel in sibling rivalry...
For starters, credit where it's due: try The Smothers Brothers' Comedy Hour on dvd.
Then for more gothic spin, Whatever happened to Baby Jane? Bette Davis and Joan Crawford starring together is even terrifying to contemplate.
For a historical slant, how about The Other Boleyn girl ...what happens to siblings when their folks are real social climbers...The 2003 adaptation is a BBC Production.
In the Chickflick category, try In her Shoes (Toni Collette and Cameron Diaz)
If you want conflict with a sweeping panormama in the background, try Legends of the Fall (a bonus is great shots of our local landscape) and A River Runs Through It. In the first, the fight is over a girl. In the second, which brother is the "good" one is the issue. If you watch both, consider it a Brad Pitt in Rural Montana double bill.
If all this viewing has you foaming at the mouth, we just received a new book: Mom Loves You Best: Forgiving and forging Sibling Relationships