If you have siblings who fight often, put yourself into super nanny mode and tell them calmly to do the following:

Sit down on the floor, cross-legged facing each other.  You have to keep your hands in your lap and not touch the other person or he will win.  Now, stare at each other for awhile.  Let your eyes show your sibling how angry you are.  great!  Now, make the silliest face you can at the other person without making any noise.

Give a couple more silly suggestions and you will usually see the children laughing instead of staying angry.  When this happens, you know you have stepped into your super nanny shoes, feeling more confident and successful as a  parent