When all six children contract the measles, the girls prefer their usual doctor, and the boys prefer theirs.
When Peter comes home from school in the middle of the day with a case of the measles, Carol naturally tries to call in the family pediatrician, Dr. Porter. When she can't get through to the pediatrician's office, Mike tries to call the pediatrician's office himself. However, what Mike and Carol do not realize is that Dr. Porter is the girls' pediatrician, and Mike tries to call the boys' pediatrician, Dr. Cameron. So it's a case of one doctor too many when both Dr. Porter and Dr. Cameron come to the house.
What's more disconcerting for Peter is that Dr. Porter is a woman. When the other five kids come home each with the measles, Mike and Carol not only have an issue in catering to the bedridden kids' every whim, but they have to decide which doctor will be the family pediatrician. Each of the six kids want to see their own doctor, and not the other. Mike and Carol ultimately come to the conclusion that they can use both doctors, and it turns out that the doctors have decided to combine their practices.