Your children don’t have to “like” each other. Most siblings don’t. But they do have to respect each other. Set that expectation with them. Have a family meeting so that no one feels singled out. During this meeting, set expectations on how everyone should treat each other. Give them examples of negative behaviors (name-calling, hitting, taking toys, etc.), and then have them think of positive behaviors that would be appropriate substitutes. Write these down, and post the list where everyone can see it as a reminder.
Then have your children role-play scenarios with each other to make the learning experience fun. Reinforce good behaviors with positive outcomes and poor behaviors with negative consequences.
For example, maybe they get one-on-one time with Mom or get to pick the dinner menu one night for exhibiting appropriate behaviors. If they choose negative behaviors, perhaps they do a chore for the sibling whom they have hurt.
Remember that the focus is not directed just at your son, but includes the entire family. If he sees everyone participating in the new house rules, he will be more inclined to do so as well.
