You will only be able to keep him if his Mom is agreeable with it. I spent DGD live until 18 doing stuff for her Mom (our daughter) so I could see her and always tried to get her Mom to take up for her and treat her right, she never would. When she was about 8, her Mom didn't want her to come visit if I wouldn't also take her other two. Her Stepdad didn't treat her right and her Mom only thought of herself and also treated her like she was a Stepdaughter also. It sure caused me lots of pains,tears and sleepless nights. I sure hope things work out for you.