Hello Chicken Lovers! I have searched for many straight forward answers and Backyard Chickens has always gave me the best answers.. However i'm coming up short on this current question. I have 12 chicks that are about 5ish weeks old...May 15th they came as day old chicks from McMurry Hatchery and had all the vaccinations I could give them.. Mareks, cocci, yatta-yatta.. They are doing awesome and so healthy. I have the on unmedicated chick starter..as well as my 4 American Buff Geese. HERE'S THE KICKER.. My greedy wants got ahead of my logic and I also bought some Heritage Barred Rocks, Sebrights, and one little silver laced about 2.5 weeks ago all were 3 days to 1 week of age.. They came from a local farm and have been fed Medicated feed. Now that it is close to time for the little ones to mingle with my big ones, I need to know - Will the medicated feed void the vaccination permanently? or will the medicated feed void the vaccine and then start back protecting the chickens? -Is it necessary to separate as in detrimental? as I only have one coop and red heelers outside so free-range is out of the question.. -If i change my medicated to unmedicated feed.. Will they more than likely fall ill.. AND infect my vaccinated chicks and geese? -OR if i change my vaccinated chickens to medicated(Geese as well).. Will that put them at an even greater risk? I have one coop fit for chickens and geese.. So the extra room for just vaccinated is not there... Should i sell the unvaccinated or is there something I can do and then cure them later if either/or becomes ill?? Thanks in advance for any advice!! -The Greedy Chicken Hoarder with a big heart and little sense!