Blended families can be wonderful—or complicated. Maria is a new mom living with her husband and stepdaughter, and she’s alarmed by the girl’s risky behavior around the newborn: trying to lift him and nearly dropping him, attempting to feed him apples, and almost spilling hot soup on him. To keep the baby safe, Maria began locking the nursery door.

During the girl’s last visit, Maria heard her baby cry and rushed in to find a dining chair dragged to the bassinet and two small hands trying to lift the infant out. Shaken, Maria grabbed the baby and told her husband, “She can’t come in here until the baby is older,” insisting his daughter stay with her biological mom for now.

Safety has to come first. Locking the door was reasonable, and the girl’s actions may be fueled by jealousy or a bid for attention. Maria should spell out each dangerous incident to her husband and ask him to prioritize their infant’s wellbeing—he can still see his daughter at her mom’s home while they set boundaries.

To avoid making the child feel rejected, Maria can gently explain that newborns are fragile and she’ll get to help and play when the baby is bigger. If her husband refuses these safeguards, Maria may need to consider separate living arrangements—because a newborn’s safety isn’t negotiable.