What makes a cast memorable in your mind? Could it be that the characters have grown on you like part of your own family? What happens if the characters you have come to love have to be replaced? Remember, it was the writers, as well as the actors, that made successful transitions happen.

The cast of “M*A*S*H” was very memorable indeed. We may have lost Major Frank Burns, but Charles Emerson Winchester was accepted in his place. Hawkeye got along with BJ Honeycutt as much as he did with Trapper. When McLean Stevensons' character was killed off, we accepted Harry Morgan as the new head of command. When Radar O’Reilly went home and Klinger took his place, it was just as if it were a rite of passage.

On a reunion of “Cheers”, Kirstie Alley admitted that she was nervous about how people would accept her as a replacement for the outgoing Shelley Long. As she lasted for the rest of the series, it seems like people took a liking to her portrayal of Rebecca Howe.

Were these changes more acceptable than the second Darrin on “Bewitched”? How about when Alice Pearce passed away and they replaced her with Sandra Gould as Gladys Kravitz? Do you also realize that there were two people that played Louise Tate? They definitely worked into the show and became an accepted part of the family.

When there were cast changes in Roseanne, it was also written into the script. At the end of one of the episodes, there was a scene with the cast where the character of Becky was talking about the two Darrins on Bewitched. Becky, of course, was the character that had two actresses portraying her.

Taking “Seinfeld” and “Friends” into consideration, and their many cast members, could you imagine the show without one of the cast? What about the girls of “The Golden Girls”? Who would we have done without? Would it have hurt to have one more addition to the cast? Think about those questions also with “The Mary Tyler Moore Show” in mind.

Should something happen to an actors contract, they might have to be replaced. How will that work into the scheme of things? If some calamity were to happen in real life, that also changes the playing field. How would your sitcom cope?

Try thinking ahead and write a few scenes that would help explain cast changes as in the examples from “M*A*S*H”. Perhaps your sitcom would be one like “Bewitched” and just have the new character enter with no explanation.