How much rent should I charge my adult child to move back home?

She is 24 years old and has a 6 year old daughter. So they would both be moving back home. But, I also have a 16 year old daughter had home with developmental disabilities and a 9 year old son. I already have a extremely stressful home environment. But, I don't want to put my 24 year old on the street. (The 24 year old is my step-daughter and it was stressful when she lived her as a teenager. All hours of the night, disrespectful, etc.) I don't want to put her on the street, but don't want to be taken advantage of either. Would $400 a month be too much to ask for her to pay rent? She makes minimum wage.

It is really stressing me out. Food, shampoo, use of the water, heat, etc. Her and her daughter would be sharing a room; which I now have to empty and figure out where to put it. Does she think that she will have permanent baby sitters as she goes out at night with friends to bars, etc.? Her dad is a bit wishy-washy and has always played the “good guy”. That really worries me. I feel trapped. She was very disrespectful towards me while she did live under our roof. She moved out when she was 17 bc she was pregnant and thought her “real mom” would be better. Now 24 wants to move back in bc her Real Mom is driving her nuts. Am I cleaning up after her and her daughter, fixing their meals, wiping their ass. argh

you dont say whether this takes in food, utilities etc

if it does, i doubt she could live anywhere else for $100pw

so perfectly acceptable

if you charge her less, she has no incentive to move out

and if you charge her more she couldnt save up to move out

so it sounds about the correct amount