Trivia: Once the first season with Terri started, Cindy no longer had "Snow" mentioned as her last name for the remainder of the episodes she was in (possibly due to the fact that this was the first season that started without Suzanne Somers completely and the producers wanted to retire the "Snow" surname altogether).
Trivia: Of all 5 roommates (Jack, Janet, Chrissy, Cindy, Terri), the only parent of a roommate never to appear in any episode is Cindy's mother.
Trivia: After Suzanne Somers demanded a higher salary, causing her to be fired, John Ritter and Joyce DeWitt stopped speaking to her. Later, DeWitt was upset about not being in the new show "Three's a Crowd," and she quit speaking to Ritter. They reconciled before he died, and Somers also reconciled with DeWitt.
Trivia: Heather Locklear was one of the actresses who auditioned to replace Suzanne Somers. Locklear was so nervous that she was afraid of sweating, so she tucked tissues into her shirt, near her armpits. A tissue fell out, and producers laughed at her.
Trivia: Jeffrey Tambor, Anne Schedeen, and Jordan Charney have all guest starred in episodes involving Chrissy, Cindy, and Terri. (To avoid confusion, Tambor's episode with Chrissy was technically an episode of "The Ropers" but in recent years played in syndication as "Three's Company").
Answer: Richard Kline and Don Knotts were supporting cast members, who could be replaced at anytime. It was John Ritter, Joyce DeWitt and Suzanne Somers who were the star vehicles they relied on to carry the show.