According to muslim personal law :

1.Can a adopted daughter be a successor just like his own son of the adopter by registered will of adopter.

2.I (am a real nephew of my real uncle),  do not have any document as a proof by which i can say in court that she is adopted child of my uncle except witnesses.

3.Are witnesses statements in court are enough to win the case or court court give importance to documents in which her adopted parents name is written instead of her real parents name.

                       Please reply as soon as possible . I will be thankful to you.