You can try to diffuse the attraction of the Houdans' different appearance by introducing something that is of equal appearance and attraction. Get creative. Look around the house and garage and see what resembles the Houdans. You might even be able to make something.
Badminton cocks come to mind. A couple of small feather dusters. You get the idea.
Sounds like your chicks need more space overall, if you're having persistent pecking issues. And they're bored! they need more space and things to occupy themselves, or they'll make trouble. Just like a Border Collie