And Then There Were Three

 is the eighteenth episode of the second season, and the fifty-fourth episode of the Bewitched series. The episode was completed by December 10, 1965.

Plot
Endora pops into the waiting room from the delivery room to tell Darrin she has a granddaughter. She even names her Tabatha, about which Samantha and Darrin are not happy. Later, Samantha's lookalike cousin, Serena, visits the hospital and Darrin mistakes her for their baby daughter (believing Endora had put a spell on Tabatha to turn her into an adult). Eventually, all problems are solved, and Darrin and Samantha accept Tabatha as their daughter's name.

General

 * This episode marks Serena's first appearance.
 * Tabitha's name is spelled "Tabatha". It will change to "Tabitha" in Season Five.
 * The character of Miss Foster was credited as Student Nurse.

Casting

 * Elizabeth Montgomery was uncredited for playing Serena.

Cast

 * Elizabeth Montgomery as Samantha Stephens and Serena
 * Dick York as Darrin Stephens
 * Agnes Moorehead as Endora
 * Gene Blakely as Dave
 * Joseph Mell as Manager
 * Bobby Byles as Fred
 * Mason Curry as Dr. Anton
 * Celeste Yarnall as Miss Foster
 * Eve Arden as Nurse Kelton
 * Cynthia Black as Tabatha Stephens (uncredited)
 * Judy Pace as Nurse (uncredited)

Source
Bewitched, Season Two episodes on Wikipedia. Retrieved on November 12, 2019.