The boys have a stronger marking of a yorkie than the girls seem to have. IMHO they all look like a mix breed. Either that or there is some mix breeding in their linage. The best judge will be you. Look them over and if you have doubts that they are not what you want, say so. Don't let anyone presure you into taking a dog you don't won't! You could always tell her you would like a VET to check him before you make a commitment. A vet should know if they are mixed.
Good luck.....let us know how things turn out.
