If nothing else, the novelization of TUC's invoking Carol being critically wounded in an attack by the Klingons as a way of explaining Kirk's increased hostility toward them at the beginning of that film could have been a nice callback.
In the prologue for the Star Trek VI novelization---Jim is at Carol's bedside after she's seriously injured during a Klingon attack on a colony she was working it. I think it is in there to add dimension to Kirk's headspace in the movie...not just anger over the loss of David, but Carol is laying near dead and he's called to deal with this because--- Spock volunteered.
The novelization is fantastic (all of them are) really.
Personally, I hated that. Largely because I don't think Kirk needed a reason for "increased hostility" towards the Klingons in STVI. He'd been enemies with them for 30-40 years and they were responsible for the death of his son and the destruction of his ship. That's plenty.
Hell, "Errand of Mercy" already gives plenty of reason for Kirk to hate the Klingons:
KIRK: Gentlemen, I have seen what the Klingons do to planets like yours. They are organized into vast slave labor camps. No freedoms whatsoever. Your goods will be confiscated. Hostages taken and killed, your leaders confined. You'd be far better off on a penal planet. Infinitely better off.
I was extremely disappointed by what J. M. Dillard did with the STVI novelization. It was pretty obvious she didn't like the screenplay much and spent half of the book trying to plug what she saw as its flaws, but IMO, she just took the teeth out of the whole thing. (Oh, don't worry! Kirk isn't
really as prejudiced as this movie makes it seem! Oh, don't worry! Spock actually asked Valeris for
permission during that forcible mind meld! Hey, here's a less funny tag on McCoy's "Bet you wish you'd stood in bed" line!

) Nicholas Meyer and Denny Martin Flinn actually took some chances with the TOS characters and had them do some surprising unexpected things in their last movie. Dillard seemed more preoccupied with sanding off all the edges than actually adapting the movie's story.