“My partner and I have been wanting children for a few years now. We are both unable to conceive. My sister is pregnant and would like us to adopt the baby. We live in California and she is in Arizona. What do I have to do to adopt?”
Every State has a method for relative adoption. It will include mother and father both voluntarily giving up their parental rights in favor of you and your partner. You will also need to have sufficient background checks and employment. The matter will proceed likely in juvenile court where the child is born.
You will need to file the proper papers with the proper authorities where the child will be born. The paperwork should be filed prior to the child’s birth.
There are forms and assistance available online, and in some cases some forms can be prepared by a paralegal. Though you may be able to figure out how to do it yourself, you might be better off finding an attorney (likely in Arizona) that is experienced in relative adoptions.