Hi again! I also had my DS with Dr. Robert Rabkin. He's retired now, but his younger brother, Dr. John Rabkin, is the one other people here mean, and also well regarded. But your sister is in SoCal, and the only one there is Dr. Keshishian.
I hope your sister will come here and read and post herself. While it's great that she has you to help her along her way, she will benefit so much more from learning all about the DS first hand.