As long as you share the same iTUNES account log in, you will have access to the family downloads, but have different ID's for
Settings > iCloud
SEttings > Facetime
Settings > MEssages > Send/recieve at
Have your family have a DIFFERENT apple id in these settings,
For the store just...
SEttings > ITunes & App Store
HAVE THE SAME ID SIGNED IN HERE; you will keep access to teh same account so Child A can have Child D's downloads and viceversa; However do note that set this expectation early; if the kids /ever/ want to have their own itunes store account they will not be able to update/redownload any music belonging to the other account and will have to repurchase them to add them to their own account
There is no exception, so if they want to fly solo, sooner then later is better.
