Children need to know exactly what is expected of them. For older children, it may help if parents write out and post rules. Don't feel you have to treat each of your children exactly the same. Each child has a different age and personality. It is impossible to treat them the same.
Children often use tattling as a way to improve their status with their parents.
Parents should simply ignore it. If children report some behavior that must be stopped, parents can stop the behavior without addressing the tattling. Parents should try not to get pulled into the position of judge in children's arguments. Parents should ignore minor conflicts and let their children work out solutions on their own. Children must not be allowed to hurt each other.