We ( my son and I) want to add some new birds to our flock. I have concerns for our existing flock as they came from a backyard breeder. This is the first time I would be introducing any birds to my existing flock. Our flock is almost a year old and free range all day so I am sure they have come across wild bird germs and have remained healthy. Is it possible for the chicks to make my existing birds sick as they have not been vaccinated for anything? The chicks will be quarantined for more than 30 days. The chicks will probably come in from Meyer Hatchey. My son is rather attached to our existing birds and would hate to order some chicks and have it turn into a nightmare. Any advice or experience is appreciated.