You are right. Your child is jealous of the baby. This is what you need to do-. First, you need to understand that disobedience is a way of expressing anger-because children don’t verbalize very well. Help her understand that it’s fine to complain to mummy if she is unhappy about something. In fact, help her along by complaining to her. Complain about how much work you need to do with the new baby, about how much time he takes up. Tell her that you are so happy that she is finally a big girl and can do a lot of her work on her own. And that she doesn’t spoil her clothes, that she can understand when you want her to do something. She will be encouraged to voice her feelings about the baby to you. And when she does, comfort her. Tell her “When you are unhappy with your little brother, come to Mummy for a big hug”