how can I create a child apple account for a disabled child over 13

My son is 14, but he has mild autism and requires us to have more control over his iPad when it comes to apps and such.

I have tried to add him as a child, but it won't let me enter his birth date, which is in 2005. It keeps kicking me to 2007.

We have always just had him part of our ID, but now that I have an iPhone, he will often get my texts if we are home and he has wifi.

Is there a way to bypass the age issue?