I am hoping to add three Black Copper Marans to my flock. The only catch is that they weren't vaccinated as chicks and were never fed medicated feed. I really want to add these three ladies, but I am not willing to take the chance of them getting any sort of disease. They are all a year old, so what can I do to vaccinate these girls or do I not have any options? My current flock is all vaccinated and is a mixture of 3 year olds, 4 month olds, and 3 month olds. Any and all advice is appreciated!