Ive been raising my daughters cousin since she was born. She is now almost 3 years old. I haven't spoken to her mother in a year and a half almost two years and I want to file child abandonment. Her dad is not on the birth certificate but is OK with me trying to get custody.. I don't know where to start. Please help.

So this is your niece, right? How to File for Child Abandonment in Texas | eHow.com

She is not biologically related to me. Her dad and my ex (my biological daughters father) are brothers.

So she is your niece, your ex-husbands brothers daughter

We were never married. But yes I guess you can say my niece.