It's fine as it is if you want to be able to request/offer something more restricted than "everything Pullman ever wrote in that multiverse". It's OK for fandoms to overlap for this exchange. (For example, see the three different Harry Potters in the tag set so far.)

But I can swap the noms currently in OUaTitN over to "HDM and Related Fandoms" if the broader meaning is in fact what you wanted. Let me know if you do.