If I would like to adopt my sisters baby, where do I start?

Is your sister wishing you to adopt her or is this a situation wherein social services is involved? The answer to this question and similar questions make a huge difference as to where you need to start.  Either way, you will wind up in family court regarding these matters but if initiated by social services wherein the child is in foster care, you need to proactively seek counsel to petition the court along with cooperation with social services to have you adopt this child.  If this is a situation that is more like a private adoption, both you and your sister need to go to a family law attorney and see what motions you need to file in your family court to begin this process.