My daughter does not have congenital scoliosis, rather she has juvenile, so I have no personal experience with hemivertebrae. However, I took my daughter to see Dr Betz at Shriners Philadelphia (and we traveled 3000 miles from Oregon) and he is certainly among the very best. I imagine in your daughter's case it will be a very valuable third opinion.
Good luck. It sounds like you are doing a great job getting all the information for your daughter's surgery.
Gayle, age 47
Boston brace as a teen for AIS
Oct 2010 fusion T8-sacrum w/ pelvic fixation, TLIF at L4/5.
Feb 2012 major A/P revision for broken rods
mom of Leah, 12 y/o, diagnosed Jan '08 with 26* thoracic JIS (age 6)
4/08 26 degrees, brace 16 hrs/day
9/08 17 deg. OOB - brace discontinued
9/09 30 deg, resuming brace
5/10 VBS Dr Luhmann Shriners St Louis
5/14 stable 4 yrs post-op, 14* T
also mom of Torrey, 9 y/o son, 16* T, stable