S.S.
I have had the same problem. My son is 10 and daughter is 8. You are going to think I'm crazy, but it worked. My children were fighting( ie. He hit me. well she pinched me first etc.)I had HAD it and this was my response. "I am no longer playing referee. Fight to the death. If we need to go to the emergency room for stitches or broken bones so be it. Then we can continue the fight when we get back. Just know that until you learn to be friends you will have no others... No friends over, no going outside with friends, no video games, no TV and I will be sending a letter to your teacher that you are to sit out at recess. I mean it!" Of course they didn't take me seriuosly. The bickering continued, until I drafted a letter to both teachers. The teachers were cooperative and one even pulled my son"s desk away from the group to isolate him in class( this mama had the same problem before and thought it was a great idea).It only took two days of no recess and restriction @ home before they were buddies again and begging for mercy. I ended it on a probationary period. Not only were they not fighting for fear of punishment starting over, but I overheard one of my sons friends starting to bicker with my daughter a few days later and my son stopped him dead in his tracks. Good luck.