Should these series entries be combined?

I'd appreciate if someone more experienced with combining and what makes a work could take a look at this page: https://www.librarything.com/series/A+Rizzoli+%2526+Isles+Novel and tell me if the two books marked as #9 in the series should be combined? Is an edition of a book that contains a bonus short story considered a separate work? I've never considered them to be such but I freely admit my grasp on the works concept is a bit shaky.

background on the story:
http://www.tessgerritsen.com/my-kindle-free-short-story-experiment/

It sort of depends. People have different ideas of how much extra material is needed to create a different work. A bonus chapter from the next book I would not consider as creating a separate work, but a story, probably unless it was very short. I know that I got quite upset when I discovered that I had a copy of a book by a favourite author without an extra story that was only available in an edition with the novel I owned.

In this case:

A) Someone has entered work-to-work relationships.

B) Both works are in the series, so it is easy to find both.

C) Lots of members have seen fit to enter the title as including the story (or at least left it that way).

D) It would need special attention to combine as both works are way above 200 copies. (718, 417)

I would be very hesitant to combine these.

>3 MarthaJeanne: Those are all compelling reasons, MarthaJeanne. Thanks for educating me about all the considerations that should go into such combinations. I'm going to leave well enough alone, but at least I can stop wondering if I should do something about it.