Are you able to make an Origin account on the website and link it to the sub-account that way?
Note: May still require a parent's email addess.
This is the correct answer. I had to create an Origin account then link the PS4 account once I logged into the Origin account following the below instructions.
The following thread includes information and instructions concerning linking, or making changes to your Gamertag/PSN ID and your EA Origin Account:
For EA games, these accounts should be linked to your https://account.origin.com/
Linking your accounts: Your Gamertag / PSN ID and Origin Account should be correctly linked when you first access an EA game online if you use the same email address for both. We recommend that you check your Origin account to ensure your emails match.
If the email address for your Gamertag / PSN / PSVita ID is different than the address for your Origin account, connect them using the steps below:
1) Open the Origin client and click the Friends button, then add a Friend. If you do not have the Origin client installed, you can download Origin for both PC and Mac here: https://www.origin.com/en-ca/download.
2) In the Import Friends menu, you can choose to "connect" your Xbox LIVE, PSN, and EA accounts. Simply sign in with your account details to connect and they will be linked.
