@Joe2862 Many people searching on AirBnB will enter the number of persons but they neglect to enter the number of pets. Lots of my guests will ask "how do I pay the pet fee" when all they had to do was include the pet when beginning their search.
Anyway, my response or welcome message to a booked guest reiterates the dates of the reservation, the number of persons, and the fact that they will be bringing pets or NO PETS. That tends to lead to the "Oh, I forgot to tell you about Fido" and then I bill through the Resolution Center and send my Pet Addendum. Easy and done.
If the person insists that the "pet" is an ESA or service animal and no fee should be assessed, they get the ESA/service addendum which is far stricter on the expected care and activity related to the service animal (not pet), i.e., up to date on shots, under the care of a veterinarian, never left alone or crated in the property, leashed when outside, wearing identification harness and with the owner at all times. It is surprising how many people will pay for the animal after receiving the Service Animal Addendum.