Hank here from Shopify.
It sounds like the account owner has not fully been transferred if it is still asking for your son's information, have all emails been verified of the transfer? Did you follow the steps listed in this guide to transfer account ownership?
All store owners would need to be over the age of 18, so you are right in transferring the ownership, and the accounts team wants to confirm. If doing the above still does not resolve the issue around the documents being asked, you would need to reach out to the live support teams as account access is needed. While we’re not able to provide account-specific support via the Community at this time, we’d be happy to continue assisting you through live chat, email, or callback.
Please visit the Help Center and log in to your store. Once you log in, search for a topic to assist with your query and the system will try to narrow down some helpful documents. Below this list, you will see the option to continue to support, where you will see the relevant options open to you to contact the live chat teams, and depending on wait times, you may be offered a callback from the team also.
Once you reach the team, they will be able to gain access to the account and see what the issue might be, and even speak with the accounts team if needed.
All the best,