Elizabeth MacRae had a recurring role as Gomer's steady girl, Lou-Ann Poovey, on Gomer Pyle: USMC (1964).
Dating Tommy's sister was a big distraction, but Howard breaks the first rule of the Big Brother system when he starts lecturing Tommy the very first time they meet. As Principal Tracey reminded Andy, students tune out adults instantly when they act like authority figures.
Goober mentions that he is an only child in this episode. On TAGS spinoff Mayberry RFD, two episodes were dedicated to Goober's niece and brother.