My nephew is 16 years old. My sister and his father are considered to have joint custody but my ex brother in law has placement. My nephew has been living with his mother majority of his life except for the year she abandoned him with me when he was 11. His father has never truly been in his life. My nephew receives a few calls once in a while but his father has pretty much abandoned him.
My sister on the other hand has pretty much abandoned my nephew again this summer, leaving him with me and not even calling him.
My nephew has expressed that he wants to live with me. When he called to speak to his mother and tell her how he felt, she told him he was not allowed to live here. When I asked her why, she informed me that it is because it is what he wants.
I treat my nephew differently when he is with me. He has rules at my house. He has chores at my house and he has punishments at my house. I feel the difference as to why he wants to be here is because I listen to him and we discuss issues. We do not yell and scream. When he receives a punishment, we discuss why and sometimes I give him a choice between 2 different punishments.

My sister has had several relationships over the years. My nephew and sister have lived in 14 different places in his 16 years of life.

Here is my problem, I want my nephew to live with me to get some stability and attention back into his life. My sister does provide a roof over his head, clothes on his back and food in his stomach. My sister does not make a great deal of money. On the other hand, I do well for myself. My family no longer helps my sister with money and that includes me. Lets just say everyone was tired of being misled. My sister does not provide attention or support. She does not talk to him or help with his homework and I guess what bothers me most is she has not even called this summer. When he got hurt this summer and I took him to Urgent Care I could not get her on the phone to get permission for him to be seen. I spent 2 hours trying to get in touch with both parents. The entire time sitting in the waiting room.

I do not want to take my nephew away from my sister but I want this kid to have positive influences and understand that his life is worth trying to make something of himself. I tell him everyday that he is going to college and I will do everything I can to help him.
How can I get temporary guardianship?