Hello everyone. I am new to raising chickens. We purchased 4 buff orpingtons last June, 2017. Since that time, we have lost three due to injury of one, hawk, and one other unknown predator....we assume bobcat. This last one happened in January of this year. Since I had one lonely buff left (Buffy - don't judge, I don't have a gift when it comes to naming), I found someone nearby selling pullets in ages from 6 mos to 9 mos. So, in February this year we purchased one silver laced wyandott (Sylvia), one red laced wyandott (Wynona), and one New Hampshire Red (Reba), bringing us back to 4 hens. I found this site through researching illnesses because first my red laced wyandott (Wynona) had bubbles in her eyes. I contacted seller and he said give ACV in water so I did. A week later no better and acting listless. I contacted him again and he said give Tylan 50. I did that and she bounced back beautifully and began laying eggs about 3 weeks ago. So, then my buff orpington (Buffy) got a swollen eye and was acting less active. I brought her into my makeshift sick bay in the garage and treated her as well. In a weeks time, she was better so I released her back out with the others. Then the Silverlaced Wyandott (Sylvia) was just walking around very slowly, and had a rattle when breathing. So, in the sick bay she went about 7 days ago. She still doesn't seem to have gotten over her illness. Rattle has improved, but not completely gone so she is still in sick bay. Yesterday, my last hen, Reba finally came down with something. I noticed her with a swollen eye, so brought her in sick bay as well. So, before all this illness cropped up, I had ordered baby chicks on line. They came last Friday (3/9). I was so excited, but now am extremely worried and stressed about them. Everything I have read about respiratory illnesses indicates my current adult flock are all now carriers so in all likelihood, my new babies will come down with the illness when they are old enough to be released outside. Is there any way to keep my current flock without placing my new chicks at risk? Is it too late anyway? I mean, since I allow my chickens to free range several hours during the day, they obviously leave droppings everywhere. So, there is no way to disinfect an entire yard too irradicate any illnesses. I'm sorry this is so long, just thought it helps to have more info than too little. Experiences and opinions of others are greatly appreciated.