Christine will retain her memories from her previous visit to Goodland but this time she's a doctor. She did that while she was back in her own world. You go girl. She also has a new face, Melissa George, because I thought it was time for a new one.
So. Would everyone be okay with her returning? She doesn't have any canon mates and I know some of the people she was friends with have changed hands but she's friendly and she'll easily convince them how fabulous she is. :D