Privacy for Under 18s
Suggestions
Add a DoB field to the signup form.
Create a quota with Profile 'Show Privacy Options' unchecked.
Create a custom module to listen for signups and if under 18, put them in the new quota.
The custom module will also listen for the 'daily maintenance' event to check all user ages, moving them to a regular quota when over 18, and removing the parental access.
All the gaining consent and initial account linking would still need to be done by admin, by hand, though.