Shelley MIGHT do the sit now. She sits pretty well now while we walk the agility courses - but I have to turn occasionally and give her the beady eye. She doesn't mind sitting next to other dogs - in fact we have a picture somewhere of her and her good friend Tori the Black Lab sharing an extra pause table while waiting in "sit" for us to complete the walkthrough. They usually sit together and are known as "The Bookends."
Oh - Logan would sit just fine next to a friend. That's why it was hard to practice. It was all the ~new~ dogs at shows he wanted to make adventure of. And I could neither practice nor discipline him there.