Ok here is the deal, the father was a druggie, got in trouble with the law, all charges were dropped except one which was found not guilty by reason of insanity. He went through treatment, came out better.
He was off most of the bad stuff, just used light stuff. Then he met the mother, she was also in treatment and didn't live with her parents (she was 17 but emancipated). Her parents were really messed up (not on drugs just freaky weird, strict and strange. just bad parents) and she had been in and out of treatment for years since she was a young teen.

He met her, she was a druggie. They lived together 3 years, she got pregnant and left him and moved in with her parents where she stayed for years. Dad got totally clean for over 10 years, went to college, found himself a great girl, a job, and had a son, who is now 4. The mother went to cali for 3 years, was in and out of bad relationships and kept using. Came back to her parents she despised and transfered custody from her to them because shes so messed up, but never told the dad of the custody change.

So the child is now 11, in custody of her mothers weird grandparents and the mom lives their as well. The grandparents have tried to totally prevent dad from being around his daughter. The mom has to at times, and other times has been very kind to let him see her. They both have refused any financial support and never requested any. The dads contact has been limited because the grandparents never liked him but he has had contact and she likes her dad and loves being a sister.
Even though she was in the custody of her mothers for most of her life shes lived most of her life in her grandparents house..with her mom. The mom is still frequently in and out of treatment but we don't have much documents against the grandparents. Now they are all telling lies to the daughter to scare her into not wanting to talk to her father or see him. (evertime he mentions visiting she says some excuse which her grandparents always do. we don;t know if they are scaring her or telling her to say that.) we don't know how to fight them turning her against us.

We live about 7 hours away, and have a lawyer already, the child has been appointed an ad litim, we want some other opinions. DO we (father and his long term partner and half brother) have a strong chance at getting full custody from the grandparents after living with them so long?? (the mothers already given her up.) or are our chances really slim??

He never tried for custody or even rights before because he believed that the mom had custody still and she as clean (she had told him she was when she moved to cali, it probably lasted about 6 months) plus we didn't have the money before.