Can I get supervised visits for my ex and our children? Upon returning from their fathers care of a weekend the children were in the same clothes I had left them in and the baby had a rash on her tummy, I am worried he isn't taking care of the correctly. He is also bringing woman that I don't know into the house and I fear for their safety. Can I stop this and get him supervised visitation?

You petition Family Court and provide as much solid proof as you can about the state of the children.
Without something criminal such as drugs going on with other women in his house, or some proof that they are the ones neglecting the children along with your ex, you have no legal recourse just because you don't know anything about who they are. You can certainly mention it.