On the page at http://pernhome.com/aim/anne-mccaffrey/fans/fan-fiction-rules/ it says the following:
“Any reference to the mark “Dragonriders of Pern®” must be accompanied with a trademark notice indicating registration and my ownership of the mark. You may wish to consult your own attorney about online and Internet law and the rules governing copyright and trademark notices.”
After writing two fanfics based on the Dragonriders of Pern books, I decided to contact a trademark solicitor based on the advice given above, and she said that since my activities aren’t in the course of trade they can’t possibly infringe on your trademark, so my best response to you would be to respectfully refer you to the reply given in the case of Arkell v. Pressdram. Just sayin’.
Firstly, congratulations on the fanfics! You join a rather elite group who have written Pern fan fiction, including Wen Spencer who wrote the marvelous Alien Taste series (also known as the Ukiah Oregon series) that Mum and I adored.
Pern, in the realm of fan fiction, has been a placed where many people have spread their literary wings or just escaped with their imagination and Mum was thrilled that her world and works were so loved.
Secondly, the purpose of the fan fiction rules was to ensure that legalities required to protect Mum’s hard work were followed (mine, too, now) so that there might possibly be a movie.
It sounds like you are following those guidelines in that your activities are “not in the course of trade” so I’m not at all sure why you’d want to refer anyone to Arkell v. Pressdram. Particularly me, as I am neither Anne McCaffrey, nor her lawyer.