Reward System for Kids. Cotton balls and Jar. When the kid fills up their jar, they get to choose something to DO (not an object). Bowling with Daddy, out for ice cream, stay up late, Go to the pool, etc. Great ideas
Teaching Conflict resolution to kids. I would add, as kids get better at this you then step out of the situation more and more - they become empowered to solve their own problems and you have less sibling quarrels.