I sit with every one of my pups when they are being groomed. My groomer even has a special chair for me.
She has become a friend over the years, but it did not start that way. I found her through friends and she is a great groomer....and I love that I don't have to leave them. Too many things can happen at groomers. I just looked until I found one that would allow me to sit. The key in that is letting them know that you will not interfere with what they are doing...and not hover when they are grooming your pups.