none of my flock is allowed to free range for the same reason. we have SO many flying and 4 legged predators that my flock would be zero in no time. I keep working with my necked necks... blue foot is still in with the Nn hens so every now and then I add another egg from that pen to the incubator.
Oh and I have been getting eggs from my Nn that lays blue/green eggs! a few of those have found their way into the incubator.
My NN's that lay the blue/green egg's come from having the CCLB in their mix, so I didn't have to worry about having to work the puffy feathered cheek's out of them.