Scent as many of those little dollar store fleece blankets with the baby's scent, and distribute them to your dogs, to get them used to the baby's smell.
Maybe get a video of babies and play it often to get the dogs accustomed to the sounds a baby makes.
Never allow the dogs to have access to the baby unsupervised, keep the baby's door closed or gated at all times.
It may be a good idea to purchase a book on the subject. As most Yorkie owners refer to their dogs as babies, the search isn't bring up too much useful info...
