Aww LL, family treasure! :D
If he says there'll be eight beans to a pod and he's your father in law, he probably ain't fibbing ;)
Quite a few longpod varieties will grow erm, long pods with lots of beans, most of them are tall stately plants so you might need to be ready with a few stakes in the corners and lengths of string.
What a lovely pressie.
Good luck, when they come up notice whether the beans are white or green and post some pics, bet someone will be able to ID the variety 8)