What would you do?

I run an in-home childcare and watch two girls(sisters) ages 1 & 2. The one year old is constantly biting the other kids. She also pushes and hits them. I've told her parents and they just don't seem to care. However, the other parents are getting fustrated and upset. Lately the 2 year old has been hitting, grabbing, and pushing the other children. She gave my 2 year old a bloody nose because she didn't like my daughter saying no. They do make up a lot of my profit because there is 2 of them, but I'm just getting so tired of them constantly beating on the other children. I've also noticed the other kids catching on to their naughty behavior. I don't have a problem with any of my other kids. I know and understand that they are still young but their parents just don't seem to care. I can't even go to the bathroom without them hurting someone.. I don't want to lose my other business because of them.