I'm sure there is a better way, but it would probably require a "weekends worth" of time to convert my entire iOS empire. When we started with Apple, "family sharing" and "ask to buy" wasn't a thing (so I'm not locked into the shared model) but I will definitely check it out - I didn't know I could create an Apple ID for my child AND share apps among all family members.
I set up Family Sharing this weekend and you are correct for a family of five it is like a half day effort including figuring out unique usernames, being asked to use the same secret questions and then fixing the settings on each iOS device. If you have a toddler hanging on you and a curious 9 old, it is exhausting. Still it seems worth it as with each iOS update iMessages is re-enabled, which would lead to embarrassment if my vigilance wavers. Also, I like the idea of the kids having their own iCloud sync/backups.
For those interested: https://support.apple.com/en-us/HT201084