- Borrow the book (I use Libby, and so after borrowing, need to make sure I click on deliver to Kindle).
- Once you have claimed the book and added it to your account, and under account settings, click on manage "Content and Devices" (this should be the link https://www.amazon.com/hz/mycd/myx?_encoding=UTF8&ref_=ya_aw_mycd#/home/content/booksAll/dateDsc/)
- Click on the "..." Button next to your book
- Click on "Manage Family Library"
- Finally add it to your kids free time library.