I'd scrub the feet/legs with warm soapy water using a toothbrush to get into all the spots. Then add Vaseline to totally smother the areas. Repeat once a week or so til all are gone. Keep them separate from your existing flock til they are all better.It seems that the best treatment is to dip their legs in petrol (!) and then apply A & D ointment, reapply the ointment on day 2, and repeat the whole process on day 3.