Recommend me a book about coming to accept your parents are aging

My wife's a surprise menopause baby (her mom was near or in her 50s at the time) so at 34 her parents are in their 80s and showing their age significantly. It's been very difficult for her to see them deteriorate, especially her father who she remembers as a very strong and capable man, and now sees as a frail and confused old man (I would argue, though, that while he seems a bit slow in conversation and doesn't quite keep up, he's still very witty and hilarious. I'd attribute most of it to Italian being his first language and his parkinsons making his accent harder to understand). I know there are a lot of books on becoming a caretaker, but her older siblings are certainly more well-off and in a position to offer their services long before she'd ever have to. It's more the acceptance that they'll never be the people as she remembers them.

I'm hoping for anything that could help her come to accept this situation and maybe find some peace in the interim. As we're discussing maybe having children, the topic of their age comes up often as we grapple with the desire to have one asap so they'll get to meet them, with the knowledge that family planning takes time and care. There's always this looming thought of "anything could happen", because even though they're… relatively healthy for their ages, her father is stubborn and both have fallen several times. They're not so unhealthy that we know their time is coming soon, but they're also not so healthy as to believe we have all the time in the world.