How to Create a Child Account with Family Sharing on iPhone or iPad [VIDEO]
Family Sharing gives family members immediate access to each other’s subscriptions, music, movies, TV shows, books, and apps, and in-app purchases
Apple Explains How Developers Can Enable Family Sharing for Subscriptions
Family Sharing can help "grow your subscription business, encourage paid memberships, and improve subscriber retention."
A Comprehensive Guide to Family Sharing in iOS 8
Here's everything you need to know about Family Sharing.