How Does This All Work?

My cousin is in her early 30s, has had a really difficult battle with addiction and mental health issues and is not stable. She has a one year old son who she very frequently gives to her parents (my aunt and uncle) to watch for days and days on end. In the past few months she has been telling everyone (including me) that she does not want him and wants to give him up for adoption. My aunt and uncle are in their early 60s and are not able to take him. Today we talked (just my aunt, uncle, my partner and I) about adopting him, if she would agree. They think she will, as long as there is visitation. So how does all of this work? We live in MD and have a 2 year old girl of our own (I am the biological mother, but my partner adopted her when she was 3 months old through a second parent adoption). There is no father that anyone knows of, and my cousin thinks he may be a product of a sexual assault (she was heavily using drugs, prostituting and stripping when she got pregnant). My aunt and uncle are going to talk to my cousin about it, and talk to a lawyer. We also have a lawyer from our second parent adoption process, so we are familiar with the adoption process a little bit. What do we do? How does all of this work?