
If you win classes with both dogs or end up with two dogs in a class you just ask someone if they will handle for you.
On Thursday I won Junior and Post Grad with my puppy and Veteran with Grandma. I asked a friend (after checking she wasn't going to be judging the breed in the next 12 months ;) ) to handle the older bitch in the challenge.
The superior handling netted the older girl the Best bitch and CC award. I then considered it only fair to let her continue her good work and go in the BOB challenge, which she also won.
I don't see why the other exhibitors got snarky, unless it meant there were too few in the class for Junior warrant points (but then she would have counted as being present for counting numbers for that as the rule says for the JW that a dog entered in a class will count if it was withdrawn but had been shown in an earlier class, so no-one can sabotage someones points.