Had we heard of this family before the fifth season? In the first episode of the fifth season, we meet Bill Boothby. He evidently plays golf with Ward, and he has a daughter, Evelyn (another conniving female who has Wally in her clutches, probably according to June).

In the episode where Lumpy drives Ward's car to the track meet, we find out Bill is now a co-worker of Ward's.

In the long distance call to Don Drysdale episode, we find out Bill has a son Beaver's age, Alan.

I don't think we ever hear anything about Mrs. Boothby.

Mrs. Boothby was living with the first Mr. Boothby. In Wally's Chauffeur when Evelyn asks her father for the car to drive to the dance it's a different person. Also Mr. Boothby in the locker room talking about wedding bells is so different from the subdued Bill Boothby in the office.