Best practices to migrate from a single shared iTunes account to family sharing Since iOS 4, my family is equiped with multiple iOS devices. I used the same iTunes account on all devices to share :


Applications
Photos
Notes
Musics
Data (game progression)


With iOS 8 Apple introduced family sharing. Firstly I didn't see any advantage in this new functionality. 
But with this post, I understand that 1 account per physical person is the new golden rule.

So what are the best practices to migrate from a single shared iTunes account to family sharing without loosing anything ?

Some data (game progression) aren't shared accross all devices, how can I be sure that my daughter will not loose her data when she will use her newest iTunes account ?
Personally I would create subsequent accounts for other family members, then you can use your current account as the "parent" or "leader" account and then add the new accounts to the family. 

You are still using your original account so you're guaranteed not to loose anything, the others should also have access to the content you choose to share with other family members.