PIP appeal for 16 yr old with appointee

Hello,

My son has a PIP appeal and I am his DWP appointed appointee. He has Aspergers.

We have been in receipt of Mid rate care/low mobility since he was five, but upon turning 16, after assessment, he was deemed to be an 'independent young person' and all the difficulties we listed (including the school support plan) pretty much disregarded. (O points)

I appealed and he was awarded 2 points for communication difficulties after I argued with their 'he speaks to friends so can speak to anyone' statement.

We now have an appeal to attend (today). I have attended a tribunal before (when he was 7) so have a rough idea of what to expect, but I wondered if anyone knew if it will be my son who is asked questions now he is 16, or me, as his appointee? (I have tried to find this out online but can't seem to find the answer).

Thank you in advance.