I'm sorry to hear about Ella's diagnosis. You didn't mention whether she has severe, moderate, or mild aplastic anemia; the difference is determined by counts at diagnosis. As someone mentioned, ATG can bring remission, sometimes for a long time. It isn't considered a cure.
The best ATG regimen according to Dr. Margolis at this time is the high dose 4 day treatment, rather than a lower dose 10-day regimen. Dr. Margolis at Children's Hospital of WI is VERY accessible, and he will talk with you, even if you are not his patient. I would recommend giving him a call. He is really amazing, and he will answer your questions.
Good luck. Feel free to email me if you would like to talk about ATG or BMT for AA.