I've noticed that, in watching M*A*S*H, the characters have relatives that come and go, according to the plot. Examples:

Hawkeye early on writes a letter home, telling his father to "Kiss Mom, and Sis...." Sis is also the one who knitted his lopsided sweater. Hawkeye then becomes the only child of a single father.

At one point, Margaret wants to borrow money from Frank for a wedding gift for her sister (who's only a captain). Said sister is never referred to again. There's also the matter of her father, "Lazarus" Houlihan, who comes back from the dead.

Radar mentions that he locked up his bicycle before coming to Korea because his sister always does something to the chain when she borrows it. There is also mention of several other uncles besides Ed. Yet, when Ed passes away, Radar must go home because there is NO ONE who can assist his mother with the farm.

Charles refers to a nephew who has fainting spells, even though his unmarried sister Honoria seems to be his only living sibling.

Potter has a son who's a dentist, and a daughter. Each has at least one child. Late in the series, when asked if he has children, Potter totally forgets about his son.

Rizzo seems to jump from being a man with a girlfriend who jilted him for a college man, to a man with a "loyal, patriotic American" wife and son.

There are probably more, but I can't think of them offhand.

In the movie, Hawkeye was the married one; in the series, it was Trapper (and later B.J.)

According to the novel, Hawkeye, Trapper and Duke were all three married and had children.

Here's another tidbit from "Officer of the Day". Radar has a brother, who is 4-F and working in a grocery. Supposedly, Radar's teddy bear is actually his brother's.