We routinely add to our chicken population each summer. As hens age they lay fewer and poorer quality eggs. We let our gals retire here and just live out their natural lives. Since the birds are free range we don't have to worry about things like coop space so the freeloading birds aren't really a problem. But we do need to keep plenty of young layers who are in their prime around.
I had ordered 100 pullets a few months ago without paying any attention to the fact that they would be arriving at the end of a holiday weekend. It is a long story but rather than getting an early-morning call from our local post office that our birds were ready to retrieve, I got a Tuesday afternoon call from the Greenville distribution center. The fellow said he could send the birds to my post office the next day or I could come on to town to retrieve them. Al ran by within an hour to pick them up.
There was only one bird who did not survive the long trip from Iowa. We got everyone else set up and so far they are doing nicely. Our daytime temperatures have been in the mid to upper 90's so we haven't even needed a heat lamp during the day.