Ha, I have 2 right now that are always fighting or bugging eachother. I can never tell which one is at fault at any given time because they are both equally capable of being the guilty party.
They are almost 4 now and should be past this, so now, if they are fighting they both go on time out, whatever they are fighting over gets taken away. They should know by now that if they are bothered and can`t solve it with words, then they are supposed to come to me for help.
I have had over the years many kids that haven`t gotten along. I just help them deal with conflict. Not everyone is going to get along, it`s life. I had one girl that could not get along with anyone (she was a princess) parents wouldn`t work with me and were in denial so they eventually left, whew.
It`s very stressful when you have kids that can`t get along. I believe that they are never too young to learn to cooperate and share and use their words.