Family Sharing of additional iCloud storage
The Family Organizer purchased substantially more iCloud data storage to back up files on the family iMac. An underage family member with an icloud.com account uses the same iMac, but the iCloud storage on his account appears only to be the (limited) free storage that comes with his account. How can this family member use the iCloud storage purchased by the Family Organizer when logged into the iMac under his own account?
iMac, OS X Yosemite (10.10.3)