Should my sister in laws kids be taken away?

My sister in law has 4 kids 3 or under 18. She has been homeless for about a year trying to stay at friends houses. She has stayed in house that use drugs like weed and also spice. We have tried to get her to stay at a home less shelter but refuses. She makes the 13 year old care for the 9 year old and the youngest thats almost 2. The 2 yr old is super attatched to the 13yr old. My sis in law has ms and says the reason why she has the 13 yr old watch the youngest is cause she doesnt want to get to close in case she dies. She also talks about killing her self. Dcfs has been called before but she has the 13 yr old to to them about whats going on. Her husband wont work and has been known for selling drugs and my sis in law also trades food stamps for pills. And sells her own pills