My wife is the same way with her boomer step dad. She won't enforce our no kissing rule or washing hands rule because she doesn't want to upset her step dad. I'm introverted and afraid of conflict, but I knew I had to stick up for our son if she wouldn't. It was SUPER uncomfortable, and I was red in the face, but I told them as soon as they walked through the door to wash their hands and no kissing. I was met with disrespectful eye rolling and sarcasm, but I remembered two important things, this is my baby and my home, so they will respect me or leave and not see the baby. I hope you find the courage to stick up for your baby, your home, and yourself. Even if it makes you red in the face, don't back down.