Ist post for me! The kenmillix affix confused me many years ago, Having seen several dogs with this in the KC reg I was well confused and actually thought the the affix belonged to a breeder of multiple breeds. As has been explained above a doggy mate soon put me right. The KC do change it I so I believe, annually I think, but could be wrong.
Many years ago puppies bred by breeders who didn't have an affix(now kennel name)& only used one name were all called Kenstaff Ken & Mildred Sames will have passed away by now I would think