My brother brought my cat over, sort of. they ended sending her on an earlier flight so she would be cleared by the time he arrived. I was there waiting for her at the reception centre, and a half hour later, my brother showed up. I don't think she needed to be accompanied by anyone at all. As long as there was someone there to pick her up.
I even had a notarised letter saying my brother had permission etc.. to look after my cat. Didn't need that either.
I didn't leave for the airport until I knew she was cleared, I called several times to make sure she had made it ok and had made it through the process. It takes 3-5 hours to clear the animal.