How do we help our children transition from pampered baby of the family to middle child? Is the resulting misbehavior going to go on forever? Someone in our Facebook group asked: "My five-year-old became a middle child a few months ago. He is so sweet and loving to his new little sister, but has been acting out: spitting, running around, saying bad things, hitting another kid in his pre-K class. He has been very difficult at home, too. He was never like this before becoming a middle child. Somebody please just tell me this is a phase." Yes, it's just a phase, Margaret assures us, citing her own experience being usurped as the baby of the family when she was five. This acting out is boundary-seeking behavior. When presented with changes in the family dynamic, kids will investigate to see if they can get away with more than they were able to previously. You can make your child feel validated in his frustration, but it's still important to set firm boundaries around unacceptable behavior. Here's the article Margaret suggests: Kate Marple for BabyCenter: Helping your child adjust to a new sibling Special thanks to our sponsor, Pampers: For trusted protection, choose Pampers, the #1 Pediatrician Recommended Brand. Download the Pampers Club App today to start earning free diapers.