i was only fifteen when my nephew was born. and my sister is drugs addicted. they live in california, while i live in indiana, and i thought my nephew was already adopted by some parents. then my grandma from california told me that we can still fight before my nephew turned 5 years old, and hes 4 now his bday is in dec. so i need to get it started asap

so since im 20 now, and i want to get him, so what is the possiblities? what do i need to do?

and remember we live different state, so do i have to move calif to get him or what? just tell me what should i do from first step, please help!