Jacqui,
Olivia's situation is complicated, quite unfortunate, and very likely unique. Still, consultations with the best pediatric specialists could be the key.
I recommend that you consider contacting the Children's Hospital of Wisconsin, in particular pediatric aplastic anemia expert
Dr. David Margolis. He has a ton of experience with this disease, including the complications that make every treatment approach a tradeoff among risks.
May I ask how well Olivia is coping with her heath issues? It's particularly hard for sick kids to maintain their mental well-being as they become teenagers, when their illness makes them different from friends and classmates just as their peer relationships and self-image typically become so important to them.