Where there are kids, there is going to be conflict. Young kids don’t know how to share, so they grab everything they see just to check if it is theirs or not. And while older kids understand competition a little better, they still fall prey into fighting with siblings in order to “win” or get attention.
Remember that even if one child starts the conflict, in order to keep the “fight” going, the other child has to participate. So the best solution is to remove the kids from each other immediately. This teaches the child who started the issue that if they fight, whatever they were doing and whoever they were playing with comes to an end. The message needs to be, “If you hurt with your words or body, you don’t get to be around anybody.” After all, that’s what we do as adults: it is called a restraining order! Separating the kids also shows the child who was hurt that their parent will protect them by helping them get away from the person who is hurting them.
After the rivalry is over, and when the kids ask to play together again, the parent says “No, because you hurt each other while playing together earlier, so for now there is no play.” This teaches both kids to have to think before they get into it with each other, otherwise their play stops.
And most importantly, when you see them playing together without conflict, be sure to acknowledge that by moving closer to them with smiling eye contact or a light touch. Then in a quiet moment later, talk about their awesome play together and play with them because of it.