Yes, you need to include him, you can try to adjust it in the app. We forgot to include my nephew once, he was only a few months old and in a carrier all the time. The reservation was for 9 and with him we had 10 so it would have been the same size table too. The staff at 50’s was so rude about it, treated us like we were criminals or something and we had to wait over an hour to be seated. I understand it can impact fire safety rules but the restaurant was not full so I doubt that was the reason.