does anyone know this book?

[growbag]

When I was a teenager (in the 80s) I read a book, can't remember the title or author, but it was American and was narrated by a teenage girl whose sister was dying of cance. I have a feeling that she was called either Molly or Margaret. The family lived in the middle of nowhere and the only other characters I remember in it were some old guy who lived next door and also a young couple who had a baby named, somewhat oddly, "Happy". Does anyone know what the title of this book is, or who it's by? I remember I really liked it and want to see if I can get a copy for my niece.

[Maddie'sMum]

Is it 'A Summer to Die' by Lois Lowry?

[growbag]

Hi, thanks for replying. That rings a bell - i'll try searching for that.
Thanks,
Growbag