Amazon Family Library Set Up - Business Insider

A handy overview of sharing via Amazon Family Library

"With Family Library, you can create a six-person Household, linking your account with another adult and up to four children. The two adult profiles can buy and share content with each other — including apps and audiobooks — and the child accounts, which still have to be using devices registered with one of the parent's accounts. 

If you have a friend or family member with similar taste in books, Family Library is a great way to save money. 

Here's how you turn it on:"

Amazon Family Library Set Up - Business Insider