Hello, Paul, Your almost daughter-in-law is lucky to have you in her corner.
As for the questions about non-invasive "changing" to invasive, it is as question of time. If left untreated, non-invasive does grow and become invasive. That is why it is so important to find it early, and to treat it. She will probably be scheduled for cystoscopy about every three months for about two years, then every six months until five years have passed, and then annually forever. Unfortunately, bladder cancer does have a nasty habit of recurring, so it is very IMPORTANT that she keep these appointments religiously,.
While most cases of bladder cancer seem to have no known cause, smoking has been shown to be a strong factor. And, as Alan mentioned, some lists of causes do include hair dressers as being at higher risk. WE have some salons here that only do cuts...,and specialize in that. She might want to consider that type of employment.
Best of luck to all of you
Sara Anne