@Maria15926
Answer to second question:
A villa appears in search results for the max. amount of guest set in the listing.
if a guest searches for more guests, the villa will no be shown and also the other villas will not be shown then as a combination, as they are separate listings and the "extra" accomodation in not in the same building (like somebody offering 2 rooms, can create 3 listings: one for each room and one for both rooms together to attract larger parties, then calenders are also linked by the "link calender" feature to prevent overbooking)
But you can at least mention in the listing you own more villas, also all listing are shown on your profile and on your homepage (which needs upload of a coverphoto !) :
https://www.airbnb.com/users/360821466/listings