How to change birthday for child account (under age of 13)

I found that my daughters date of birth was incorrect from setup and needed to change it as she is over 13.

IMPOSSIBLE to do it in one step. Spoke to Apple support with no luck so the hack goes as follows

1. log into appleid.apple.com with the child account
2. go to settings and change date of birth to 13 years before today (13th birthday is today) this then sends an email to parent account to approve
3. log into parent account and approve
4. enjoy the rest of the day and sleep well over night
5. the child is now over 13! (This is important)
6. repeat step 2 BUT put in correct date of birth which can now be over 13 years old
7. approve with parent account once again
8. ALL COMPLETE!!