I read Yesterday's Children (a title which to me made no sense to the story) once upon a time
Well, Gerrold started off intending to write a novel based on his rejected Star Trek
outline about a centuries-old generation ship whose human occupants had forgotten their origins (which he eventually wrote as the Bantam ST novel The Galactic Whirlpool
). The title worked for that story. But once he started writing about the new ship and crew and backstory he created for the non-Trek version of the novel, he got so caught up in it that it caused the story to veer off in a totally different direction -- yet for whatever reason he didn't change the title. At least, not until he wrote the expanded 1980 version of YC, which was originally published under that title but was later reissued as Starhunt
and liked the twist at the end.
The end of which version? The original book ended at Chapter 28. The expanded version added eleven more chapters after that and totally reversed the ending of the original. I liked the original ending much better, and felt the expanded version was something of a copout.
Fortunately, the expanded version (which is the one I have) doesn't seem to have altered the content of the first 28 chapters, just continued the story past them. So I can just stop reading at the original endpoint if I choose.