My first thought is to absolutely, under no circumstances, let your dog bite the 14 month old child! That is completely unacceptable. Failing to do so could instill a fear of dogs into the child, cause you to lose your friends, force you to have the dog put down, and perhaps even be sued. As Steve said, lock the dog up if you must.
I'm sorry to hear you've got a mini-dauchsund so ill-tempered towards others. My family has a couple and they are the sweetest dogs I've seen. But I remember some neighbors, many years ago, who had a very mean mini-dauchsund that would bite and nip visitors. (I really loathed that dog and hated visiting there.)
My suggestions (based on minimal knowledge of dogs) are two fold. First, talk to a knowledgable trainer. They should know as much or more than us random internet yahoos

Second, I've been told that one method of training puppies is to ignore them when they misbehave. They are pack animals and one to be part of the crowd. When your dog misbehaves, you walk away from him, showing no attention. The dog will learn to stop the anti-social behavior.
Good luck! Miniature dauchsunds can be fantastic pets. I hope yours overcomes the desire to eat the guests
