I would get in touch with Bookerville and see if they are willing to work on that with you. As what they would need to do is make a master unit, that is made up off all the sub-units. If available, the guest would book the master unit which would block off all the sub-unit calenders. Shouldn't be too difficult I wouldn't think. Our software, Bookt has this feature.
Seattle Oasis Vacation Rentals