I was diagnosed with this at an early age and had the injections, medications etc which was not pleasant - so I feel for both you and your daughter.
I have lived on a concoction of garlic & cod liver oil capusules (high strength) every day and as well as watching what I eat - certain foods will make it worse - and I have managed to keep going.
Some advice that was given to me was to always make sure that I watch my weight and keep up with any exercise I was able to as this would help.
Over the years this advice was invaluable as I swim at least once a week and am still able to take part in badminton. Yes it aches afterwards but the fitter I am then the less it hurts. Last time I went to the athritis specialist she was pleased that I was still as mobile as I am at the old age of 50. I do have to take pain killers and anti-inflamitory drugs some days but not as much as others.
I hope that this helps - there are support groups for this problem and if you google it you should be able to find a group in your area.