I don't know about the teenagers end, but the Parents need to get on Marc Feldman's website and also immediately read his book 'Dying to be Ill'. Because the sooner they can nip this in the bud, the less damage there will be. Not just physical and psychological damage to the teenager, but psychological and financial damage to the parents, and serious, sometimes fatal damage to the family unit.
Edited to add: The first thing they need to do right from the start is to give absolute minimum of attention to any of these fake medical needs. Absolutely as little as they can get away with without being totally obvious about it. Then, at the same time, a lot of high quality attention when it's to do with anything not to do with medical bullshit. Again as much as absolutely possible without being totally obvious about it.
That might be enough to steer her away from this if its not too intrenched.
also, if they are sure there is no actual medical need, then they should be completely forbidding her to take crutches or visible aids to school. And let the school know that its for attention and theres no medical needs. That way she won't get coddled by staff and allowed to miss P.E. etc.