Original owner of Family Plan Account left and now existing memebers can't access the account

Hello, @lindseymgall! We want to help you gain access to the account.

The account holder will need to complete a Transfer of responsibility to switch the account your name or someone else that wants to be listed as the account holder. Here is how to transfer billing responsibility for a wireless number from one AT&T account owner to another. They can start the transfer online, and the future account owner can accept billing responsibility online. To begin the process follow these steps: 

1. Go to att.com/tobr.
2. Select Start transfer.
3. Read the tips and then select Continue.
4. Enter your ID and password.
5. Follow the prompts.

Keep in mind: 

• You can transfer one line or multiple lines on the same account.
• You must pay off or transfer any device installment plans with the lines subject to a transfer request. Learn how to pay off an installment plan
• You must pay off any accessory installment plans associated with wireless lines you want to transfer.
• You'll lose any voicemails associated with your lines when the transfer is complete.

Once they have completed the Transfer request to merge your wireless lines on your account. You will then accept the billing responsibility. As the new owner of the account, you must meet these requirements:

• Be at least 18 years old
• Complete a credit evaluation when accepting the transfer (You may be required to pay a deposit.)
• Accept the remaining contract term from the date of the transfer (if applicable)

You'll receive one final prorated bill, which covers charges up to the date the transfer of billing was completed. Visit our Billing Responsibility help page for additional FAQ when merging two wireless accounts. Let us know if you have any questions. Thank you for contacting AT&T Community Forums. 

Rachel, AT&T Community Specialist

Have you tried gaining access to the online account? All you need is the user name which is probably an email address. If you know that, you should be able to reset the password by clicking the forgot password link since it will send a confirmation code by text to a phone number on the account that you select. Once you have account access, you can set or reset the account pin.

Thank you for your response and effort to help, @sandblaster. This has been such an absolute nightmare - I can't even explain the lengths we gone and this has been the last resort given every other avenue I've tried has been a dead-end. As far as your recommendation, I do have access to the online account. When I log in and request transfer of billing, it says I cannot do it online and must call support. When I call support, I am not able to provide the correct pin, nor are any of the social security numbers we have matching whatever they still have for the 'account owner.' I've tried to update the account details (number, security info, pin) online and it still requires a confirmation via the account owner via text to confirm positive identification for security purposes (which I totally get) but whatever number they have tied to the account is not one of our active family plan numbers and we aren't able to validate security text proceed?! Is it possible to reset the account pin or social for the account owner online without authorizing the security request via text first? Thank you again in advance for your help.