Supervised visits changing to ???

My children's mother has only supervised visits for 4 hours each Saturday due to her unstability and perpetual drug abuse. I know that she can have the visitation re-evaluated at any time. Their mother has been in and out of their lives since mid-2004. During her 4 hour visits, she continually has her friends, other children to keep them occupied and boyfriend over istead of focusing on them. She doesn't take her full visitation take most weekends and makes excuses on why she can't take them the other weekends. The supervisor of their visits is the lady she lives with now and she doesn't do a very good job but nobody else wants to deal with their mother. My question is this: What would typically be the next step after supervised visits for 4 hours a week? (unsupervised for 4 hours or more, supervised for more than 4 hours) Their mother doesn't have their best interest in mind and hangs out with a bad crowd for the most part so I am very nervous about their safety.