Ask HN: Does anybody know a way to increase the odds of gmail account recovery?

A little over a year ago, my adult son was in a car accident that resulted in a coma and a severe brain injury. As months passed with little sign of progress, it didn't seem like he would ever be able to use his Google Fi phone anymore. However, we were reluctant to give up his phone number because it seemed so permanent. The kind people of Google Fi helped me park his number on Google voice. I didn't have his password; so I couldn't access the account, but they did it for me.

In August, we had a bit of a miracle. It was like a switch flipped in my son's brain. He started talking again, and was soon able to get online with his Chromebook. However, he didn't remember his passwords - which is understandable. His memory of 2016 and early 2017 is filled with holes at best.

We were able to recover his personal gmail account that he opened in high school. However, we have not been able to recover his 'adult' account with the phone number parked on it.

Here's the thing - my phone number was one of the recovery options. I am able to receive the verification code and enter it. His teen gmail account was another - we are able to retrieve that verification code and enter it. I am also able to confirm the month and year that he opened the account, and answer the one security question. We have tried from my home internet - which has an IP he frequently used as well as our work Internet. However, Google's automated account recovery option still says it can't verify that it's him.

I know it's silly, but we'd really like to get his phone number back. It's just a small piece of the 'old' him that we would like to restore.

The kind people at Google Fi can't help with this one. And, there's no human at Google to escalate account recovery to. But, does anybody know a way to increase the odds of getting the automated system to restore the account?