I want to purchase these 3 day old Silkie chicks from the feed store. They have not been vaccinated for Mareks. The guy said it's fine, but I don't want to bring them home and have them die. I also have a small flock of 5 other chicks that have all been vaccinated already. They are 1-3 weeks old. Can I buy the vaccine and still vaccinate the 3 day olds? Is it bad to mix the new unvaccinated Silkies with the other 5 babies? I need to know asap, as the feed store is holding them for me, since they are otherwise sold out. I just worry that they have already been exposed since they are at a feed store. Any advice? I read that you can vaccinate at any age, but so much mixed stuff I am reading. I am so new at this, and all I know is I don't want to have any of them die on me. It's too sad......Thanks!