Sometimes we can try all the methods in the book and unfortunately it can turn out to no avail.
It sounds like you have tried all the sensible options with her hair. Anything that weakens the hair damages the hair so keep away from harsh chemicals.
The only thing would be to use an ultimate strength mousse/ styling product unfortunately our hair changes over time or with medication.
The Team at MatthewDavid Bespoke Hairdressinghttp://www.matthewdavid.co.uk