When one sibling says a negative thing about the other one in private to you, as the parent, you shouldn't dismiss the negative feeling. You should let them get it out because the more they can get out the yuckiness, what they don't like about their sibling, the more room there will be to like the sibling again. The sibling relationship is very complex. If one kid says, "I hate my brother," and you say, "Yeah, you hate your brother." The kid is probably going to say, "Well, no, that is not exactly right. I like him, too." It's very complex. Don't freak out when they say something negative about another sibling. Let them say it. So, a young child who has a new baby in the house says, "Mommy, I want you to take the baby back to the hospital," or "Give the baby away," or "I hate this baby." You can say, "I could see why you would want the baby to go away. Mommy has been so busy with the baby. Maybe you feel like mommy isn't giving you enough attention. Is that what's going on, honey?" So you attune to what's going on. You allow the negative feelings and statements come out. You help the child, in that way, calm down about what they are upset about. That way, there is room to feel good about their sibling.