Adopting my step daughter - problems

Before I married my late wife ( died last year from cancer ), her mother (my mom-in-law) adopted my step daugther (8 years ago). She has been using her granddaugther to collect Social Security checks.

I have been supporting my step daughter, I pay for her medical, food, clothing etc and she lived with me 95% of the time. The grandmother would watch my step daughter when I goto work.

Since my wife past away last year, my step daughter wants me to adopt her and change her last name to mine. Her grandmother intends to collect the social security checks till my daughter becomes legal adult. If I wanted to fight my mom-in-law for adoption, will I have a good chance of adopting my daughter ??????

How long have you been in the childs life, total.. and where is the bio dad ?

I have been in her life since she was 3 now is she is 13. Originally my in-laws adopted her (when she was 4) so her real dad would have nothing to do with her. He was into drugs and abused my late wife. That may have been the orginal plan, now my mom-in-law (widow) says she cant afford to give up the Social security checks.

When my wife was still alive, we supported and raised my daughter, which was ok with the grandmother..Since my wife passed away last year from cancer, my mom-in-law still lets me make all decisions for my daughter.

What stinks is that my daughter asked me several time why I dont adopt her...