My character, E, is seventeen when this all starts. She's very fond of her best friend's little sister, S, who's four. S hero-worships E. They're basically sisters in all but biology. When S's family are murdered, she ends up in foster care. E visits her almost every day. S is miserable in foster care, and her foster parents aren't particularly well equipped to raise a four-year-old who saw her family murdered, so E decides to adopt S once she turns eighteen. E can support S, and she's been accepted to a top university and into an officer-training program (which does allow people with kids) for the military. (I'm not sure if that would count for her or against her. On one hand, the government's already decided she's trustworthy; one the other hand, she might have to be separated from S for long periods.) E's the oldest of six, so she has experience with kids. S wants to live with E.
What would be the process for E to adopt S? Would she even be allowed to? I know there would be a home study, and E would have to take parenting classes, but I'm not sure what else would happen. I know that usually the potential adoptive parents' first meetings with the kid are supervised, but would E's have to be, given that she was a big part of S's life before her family was murdered?