I know nothing about pox, but always thought it appeared on the skin, not the beak itself. I'm not saying it's not but, I would look up beak necrosis as a possible alternative also. It could be some kind of fungal thing too. Do you have a vet that deals with birds? You might take one in and let him know you have several more at home like this.They are all silkies about 2 1/2 months old.