I've tried to leave my boxer in the kitchen with the baby gate up, a couple of times, and that didn't work for me. He managed to knock it down and I came home to a boxer roaming the house.
Not happy with that. Will your lab be ok to be left unsupervised with your yorkies? My boxer is ok with my yorkie, because Lucky can hold his own if Mosley is being too playfull. But I can't leave him alone with our latest edition Bella. She only weighs 1.9lbs and Mosley is 47lbs. Too scary.