Hi @Steve3,
I believe you could be discriminating against someone with a disability if you raise the security deposit because of their service dog. Here is an article about service animals and landlords (I know you are not really a landlord though).
I don't think you could increase the security deposit once someone has made an inquiry. If you worked something out with the prospective guest, you could decline him/her, change your security deposit, have them inquire again, and then change it back to your original SD.
Also, if you already agreed, you may be able to contact CX and see if they could manually change the SD for the one booking.
Cheers
Dave
David
Superhost Ambassador ~ Host Club Community Leader ~ Community Expert ~ Experienced Co-Host