I thought I read on here thst we chose one UEFA chose one and as we were the defendant we chose the president from a CAS list and UEFA had to agree with that choice, as they did, otherwise CAS would appoint a president if City and UEFA could not agree on the president City chose. I could be wrong.
Normally that is true, but on this occasion UEFA let us chose two. This is a quote from an article in The Athletic, i'm pretty sure it's factual:-
"UEFA also allowed City to select two of the three judges making the decision at CAS. Normally both parties choose one each and the third is nominated by the independent body which runs the court but UEFA bowed to City in their desire for a quick hearing."