Yeah, the faster you take action the better.
you might not be able to completely stop visitation right now but you can at least make them feel safe until the courts can come up with a final solution

This is such a heartbreaking story. It always amazes me how any parent can put their children in harms way like this. I think your statement that they are drug addicts and alcoholics says it all. God bless you for caring so much about these children. Don't give it up you will find justice for these kids in the end.