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