Bedding in crib - am I overreacting?

My husband's grandma (my baby's great grandma, 70 years old) has been watching our daughter for about 3 months now, usually twice a week but sometimes just once a week. My baby is 6 months old.Before letting her babysit, I made sure we sat together and had plenty of time to go over our rules for feeding and also safety standards for naptime. Specifically no blankets/pillows and always on her back.Maybe two months ago, I saw she set a comforter down in her pack n play crib. I told grandma absolutely no blankets or comforters. She apologized and said no more. I made sure that if she felt the room was too cool to show her the thermostat and she already knows where baby's extra warm clothes are.About a month ago, we came home to find baby napping on her stomach, something she hadn't done herself yet. (She sleeps on her side when she wants to roll but not on her belly.) Grandma said yes, she put her down on her belly. I was firm but kind in saying that was unacceptable. The next time grandma came over, I printed an abundance of scientific and medical studies outlining why "back is best". In these articles it also mentioned no bedding beyond a sheet until baby is a year old, once again.Today, after grandma left, I find the same comforter down in the pack n play, which she mentioned baby had taken a nap in earlier.In my mind this is strike three - I've gone over safe sleeping 3 times now. Grandma always touts "but I raised 4 kids!", crap like that. I've spoken my own opinion aloud and also provided reasoning in the form of medical studies on safe sleeping and reducing infant death.Am I overreacting if I sit her down and tell her I'll be making plans to find a replacement babysitter because of this? I don't want my baby to be a statistic and I'm tired of having to correct her on things that are very black and white in my mind. I can only imagine the other things regarding safety that will come up later. At the time, having a free sitter sounded amazing, but honestly I'd rather pay if it meant following safe practices. via /r/Parenting https://ift.tt/2BT1Ooi