Radiation for cancer is very tightly targeted, only a small area is affected, the second ovary could have been completely spared. Nowadays, not all chemos will sterilize the person. 20 years ago, it was a pretty fair bet that the chemo protocols would have sterilized her, so unless she froze some eggs ahe would not have biological children, but now the damage is much much less. Surviving stage 3 ovarian is pretty miraculous in and of itself.