Results if anyone stumbles upon this:

* When adding an item, its id, its parent id (if it has one), and the story id show up in the /updates endpoint.

* When editing a comment, the comment id and the story id show up in the /updates endpoint.

* When deleting a comment, its id and the story id show up in the /updates endpoint, but not its parent id.

* When kids order changes, their parent id and the story id show up in the /updates endpoint, but not necessarily the kids ids.