Apple - Sharing iCloud storage between family members

Update 2017/2018: It appears Apple finally allows sharing iCloud storage between family members (see the newly accepted answer). Glad to hear it!

Original:

The correct answer is No, there is not. Apple does not let you share iCloud Storage with family members, unfortunately.

Here's a forum link where this has been discussed:

https://discussions.apple.com/thread/6543858

You can share your account and password, but then the storage is yours and not really sharing with a sub-account. Each individual Apple ID gets their own paid/gifted/free storage quota and any one account can bump up their storage only and it doesn't affect any other AppleID storage capacity - family membership regardless.

This feature is coming in iOS 11 (see iMore). From that page:

.. yes, now you can share that data with your family, with up to six people using one storage plan for backups, files, and photos. Presumably, each family member's files are only available to that person, unlike, say, Family Sharing of iTunes, iBooks, and App Store content.