diary-list-entries-hook is a variable defined in `diary-lib.el'.
Its value is

  • This variable may be risky if used as a file-local variable.

Hook run after diary file is culled for relevant entries.

If you add `diary-include-other-diary-files' to this hook, you
will probably also want to add `diary-mark-included-diary-files'
to `diary-mark-entries-hook'. For example, to cause the fancy
diary buffer to be displayed with diary entries from various
included files, each day's entries sorted into lexicographic
order, add the following to your init file:

(setq diary-display-function 'diary-fancy-display)
(add-hook 'diary-list-entries-hook 'diary-include-other-diary-files)
(add-hook 'diary-list-entries-hook 'diary-sort-entries t)

Note how the sort function is placed last, so that it can sort
the entries included from other files.

This hook runs after `diary-nongregorian-listing-hook'. These two hooks
differ only if you are using included diary files. In that case,
`diary-nongregorian-listing-hook' runs for each file, whereas
`diary-list-entries-hook' only runs once, for the main diary file.
So for example, to sort the complete list of diary entries you would
use the list-entries hook, whereas to process e.g. Islamic entries in
the main file and all included files, you would use the nongregorian hook.

You can customize this variable.