Having a listing for 2 neighboring houses

[Josh334]

I have 2 independent listings but I want to have a 3rd one that combines the advantage of saving them booking fees (only have to book 1 property) but also target the audience who are looking for properties that can house more guests than just 1 of the houses.  How can I do this?  Calendar syncing would be a must, because I can't run into a situation where one of them is double booked.