Germs and family issues...

So I'm very cautious about germs. Nursing school made me very aware of things. Anyway, my family understands my concerns and respects my wishes to not kiss or touch the baby's face. My husbands family, however, doesn't get it. I told them about handwashing and stuff and not to kiss her but it's like they think it's okay now that she's 8 weeks. They kiss all over her. Yesterday, I looked over and my husbands sister had her finger in her mouth. I almost lost it. I politely told her to remove her finger and she did but I'm still so shocked. Before that, she was about to let the baby lick her dorito fingers to have a "taste." She didn't get the dorito fingers in because I stopped her, but then she had them in her mouth 10 minutes later. How do I tell them, for the millionth time, not to kiss her or touch her face? I don't want to look like the snotty wife. But I also don't want my baby sick. They just don't understand. I'm to the point where I don't want them over anymore.