Sorry but I had to giggle on the laid back, mellow, docile personality. Are you sure you want a yorkie?
As for the deposit I can understand your concern. I too accepted a deposit on one of my males and wondered if "he" would be like what the new owners would want. I would hate for them not to love him because he wasn't what they wanted in the long run.
Very good question. I wonder if maybe you should post this question in the breeders section. I too would like to know what they would do. Return the deposit or maybe keep a portion because there would be more time and money invested in the puppy. I will keep up with this post.