What are the penalties in Illinois for a 13yr old girl molesting her 5yr old brother?

Found out last night that my 13 yr old step daughter has sexually molested my 5yr old son! I called the cops and he asked what happened and talked to her but of course she said she didn't do it. Now this girl has been in a heap of trouble lately with alot of theft and breaking and entering, she goes to court in a couple weeks for that stuff. But this is a new thing. The cop said he would file the report and get in touch with child advocacy to call us to talk to both kids. I just want her out of my house, she is very uncontrolling. I just want to know if they will do anything to her and what the possible penalties are for this. She is already being charged with two Class 2 Felonies for theft and breaking and entering. I am so stressed out about all this and I just want to know what might happen!