Enable Family Sharing on Existing Devices with Same Apple ID
How do I enable family sharing on devices that are already set up? They all use a single Apple ID account. (Users were set up long ago when Family Sharing didn't exist, in case anyone wonders why it's this way). I've set up each user with their own Apple ID so I can transition them to it.
I'm looking for the workflow to ensure that all apps and their data (e.g., game levels), notes, etc. are accessible after the transition from the existing Apple ID to the new ones. Is it as easy as logging out of the Apple ID on the device, logging in with the new one, sending an invite from my account, and using them? It seems that would be it, but nothing I've found online indicates whether data will be lost or inaccessible during that transition.
I don't like having all devices on one Apple ID because I've had addresses and other things shared when I didn't want them to. It's too easy for, say, my daughter to click a dialogue box and start receiving my messages or me hers (which has happened).
Thanks.
iPhone 6, iOS 11