In addition to CBS' The Munsters, Joe Connolly & Bob Mosher's Kayro-Vue Productions sold a sitcom to NBC for the 1964-5 season as part of a network programming experiment.
90 Bristol Court was the umbrella title for a 90-minute block of sitcoms airing on Monday nights. Two of the three components, Harris Against The World (Jack Klugman's first starring vehicle) and Tom, Dick, & Mary (with Joyce Bulifant and a pre-Ironside Don Galloway), failed to get out of 1964. That left Karen as the lone survivor.
Karen, to some extent, was in the mold of the "Tammy" movies that had starred Debbie Reynolds, and, later, Sandra Dee. Newcomer Debbie Watson was cast in the title role, with Richard Denning (ex-Mr. & Mrs. North) as her father, and Gina Gillespie, sister of former Mouseketeer Darlene Gillespie, as Karen's younger sister. Sadly, Karen finished out the season, and was cancelled.
So where did NBC go wrong? Mondays, back then, belonged to CBS with The Andy Griffith Show, To Tell The Truth, & I've Got a Secret. It might've been a better bet to try 90 Bristol Court on a different night.
The Beach Boys performed the theme song, and some think that Brian Wilson wrote it. Somehow, I doubt that very seriously, as this might've actually been written by series musical director Jack Marshall, who also composed the kickin' themes for The Munsters. Judge for yourselves.
Universal, undaunted, gave Debbie Watson another chance the next season, this time in a series version of Tammy, for ABC. That also flopped, cancelled after 1 season. We'll look at Tammy another time.