My youngest sister (20) has a 3 month old baby girl. My next younger sister (23) is careless while holding the baby. The mother, our parents, our older sister (30) and myself (29) have all commented to her in various ways ranging from as an aside to near argument that she needs to be more careful. She doesn't often support the baby's head and neck or holds her in positions that could easily result in dropping. Today she was scolded 3 separate times in less than an hour for her careless behavior. I asked her today if the baby needed to actually be injured for her to understand that she needs to be more cautious. She responded that she knows what she is doing and we are all being overprotective. My parents have 7 kids between them from their previous and current marriage and this baby makes their 7th grandchild. I assisted my older sister very closely while her two kids were babies and I have helped many friends for years care for their infants so none of us are newbies when it comes to babies.
I know she is young and this is the first time she has really been around a baby, but how can we get her to understand that she needs to exhibit more caution while holding a baby?