A 55 degree congenital scoliosis which has progressed in the past years needs intervention. Without mincing words, your daughter would require surgery.
Unfortunately, physiotherapy or yoga have not been proven to be useful. Bracing has not been found to be useful in stopping progression of a congenital curve. They have better value in treating idiopathic curves.
Regular assessment in terms of clinical & radiological, is mandatory. I wonder if standing erect X-rays of whole spine were taken and the cobbs angles measured on a regular basis.
Remember; a 4-6 degree increase a year is actually 40-60 degree increase in the next 10 years! Any surgery is to mainly to stop that progression.