So sorry you are going through this. I know how keeping up with stepkids can be exhausting when their BM does nothing and puts it all on you. You are very kind to do all this for someone else's kids. They are lucky to have you. 

I can see how lice might not be enough to prove neglect or abuse to CSD, but where there is smoke, there is fire. I wonder what else is going on over there? I hate to suggest this, but it sounds like the stepkids want to stay with you, and not go to their moms. What is the reason? Can they take a video on their phones each time to record the conditions they are living in? Can they record any kind of verbal abuse or let you know when they are left alone/without food for long periods of time? Then you would have some ammunition for the court. 

To me, the situation you describe warrants a call to DCFS. Lice once, maybe even twice wouldn't. But lice repeatedly, not enough food, lack of supervision, nowhere to bathe, possible exposure to drugs or paraphernalia... That doesn't meet the minimum standard of care, at least not where I live.

I volunteer as a court appointed special advocate for children in foster care, and I can tell you that the case I just wrapped up, the children were removed from their parents' home for less than what you've described. And I live in a large metro area where the system is quite overloaded and they will bend over backwards to avoid removal. Again, I hardly ever advise people to call because the system is so bogged down. But this is extreme neglect - particularly if there are children who live in the home full time. 

If you call anonymously, and BM accuses you of doing it, you can plausibly deny it. It just as easily could have been a teacher or other mandatory reporter. Just be prepared with ALL the facts only, no emotions or opinions. And know that your home would also be inspected. Worst case scenario, it's a wake up call for BM to get her **** together. Best case, DCFS orders supervised visits at a center or other neutral location until she can pass a home study. 

Here's another vote for calling CPS. No child should have to live in those conditions.

You need to have kids talk at school to mandated reporters.  Tell them to talk a few adults there and have them report it.  You might get somewhere then.  Teachers, guidance counselors, etc.   Make a doctor appointment and have the kids talk about home life.   The more mandated reporters you get, I would think help your case.  

And.... as Survivingstephell said ^^^^^  Get the kids in front of every mandated reporter you can. Docs, therapists, school counselors, teachers, etc........  

You can get it on Amazon. I also find adding peppermint oil into their shampoo helps prevent catching lice. For treating lice I have found the Cetaphil treatment the best non toxic method. You could use that treatment every time they come home if you wanted. I agree with everyone else about CPS. You can also try speaking to the counselor at their school (all schools if half sibs are in a different one). Sometimes the school can find out if there are underlying issues leading BM to be overwhelmed/unable to handle the children's needs and refer to resources available to help with the issues. The other parent may be less defensive with the school. And if not, school counselors are mandated reporters so if BM won't work with them then they will report her.

Isn't interested in prosecuting BMs plain and simple.   Real child abuse by BMs and their boyfriends do not get investigated.   Too dangerous.

These judges are probably getting a kickback for how many times they can rule in the BM's favor.