Thinking about it, there is a possible way out if you don't have separate iTunes/iCloud accounts already. If you're not using the email address on the iCloud a

Thinking about it, there is a possible way out if you don't have separate iTunes/iCloud accounts already. If you're not using the email address on the iCloud account with all your iTunes purchases, simply sign yourself up to a new one and migrate your data over, then remove contacts/calendars/etc from the account with all the purchases and use that one for signing into the iTunes store on all the family's devices.