It's hard to say exactly since there are many upper resp. infections it could be, and I'm assuming you don't have a definitive diagnosis since you didn't say. A good diagnosis would require lab work or a necropsy. I would certainly keep her isolated until the round of meds is done and you do...
I tend to operate with an abundance of caution with sick birds. I personally would not put a sick bird where I was going to raise chicks. Too many variables for me to find the risk acceptable. Viruses vary in survival time on surfaces depending on surface materials, humidity, temp. etc. And...