Thank you for the help! However, I am wondering if there are any issues with doubling the size of my flock. Should you only add a few each year or can I add many in just one?
That absolutely does not matter. When a broody hatches, she can hatch out 10 or more at one time. If you get chicks, you will want to watch for bad pecking, because if it gets bloody, you will have a problem.
If you are adding anything besides day olds, you need to quarantine for at least 30 days. I can't tell you how many times I've seen people lose entire flocks because the new birds they added "seemed fine" or "looked and acted healthy."