A1.  I watched a friend of mine say to her children, "You need to learn to solve this by yourselves."  She would not jump in and be the mediator, though she would supervise and make sure they were being respectful to one another.  After doing this over and over again, her children learned how to negotiate, apologize, and cooperate.  I tried this with my children, and it actually worked!  They are a lot smarter than I gave them credit for.