There are a lot of details here that we do not know so I will answer the best I can without this.
First, we do not know if she has legal status in the US. If she does not have legal status then first and foremost, she should apply for DACA if she qualifies and this will depend on when she entered the US and how long she has been here. Have her look into the rules for DACA here https://www.uscis.gov/humanitarian/consideration-deferred-action-childhood-arrivals-daca
Second, although your family can adopt her if you wish, unfortunately that will not grant her US legal status in the US. She would have had to be adopted before turning 16 years old for that. If you want to adopt her just for her to be able to legally live with you, that is not necessary. Speak to a family attorney. Your family will need to petition for temporary guardianship in the state you live if her father is willing to give it.
Good luck to you during this process and I hope this answer has helped you!
If you are not satisfied with my answer or if I did not understand your question correctly, please ask me for clarification and I will be glad to clarify. Your satisfaction is my goal.
Please kindly remember to issue a POSITIVE RATING now before you leave this page by choosing from the ratings. This is very important since it is how I receive credit for my service from what you paid.
This question will NOT close after you rate me even though it says "To Finish..". So after rating me, feel free to ask me any follow up questions at no additional cost .
Any bonus you wish to provide will be very appreciated.
If you have other NEW questions in the future, you can make sure that I answer it for you if you start your new question post with the words "FOR JENNIFER " or write it in the Subject Line.