I will help as best I can. I know the facts about weddings but for each couple it is different. I'm sure that there are others here who would be willing to help.

[Cacti weren't something that the Cat had assumed were part of marriage ceremonies but human traditions were strange to him.]

There are cactus in Non-Fiction that could be part of the ceremony.

If there isn't a specific type of holy person that you need, the Head Librarian might be persuaded to perform the ceremony.

[Yes, that would be good for his friend. Something positive to look forward to instead of constantly draining his energy for the Library.]

Actually I think he would be honored if you asked.