I am working on a mixed use project that consists of retail, residential and office spaces. They all rise on a common underground parking lot. The retail, residential and office spaces rise as visually separate "buildings" (i.e., with different facade types), although they are all adjacent to each other up to the fourth floor with connections among them (as if three office and residential towers at each corner of the retail center). USGBC's "Guide to LEED Certification: Commercial" states that different buildings on the same site owned by the same owner can be registered as a group but "individual building registration and review fees apply". How does LEED define "building" in a group certification? Do we register and pay for four building projects (three towers and a retail complex) separately, since they have different functions, as well as a master site? Or can we assume we have one "building" with different functional zones as one physical block? I am assuming that the entire project can be registered as a v4 CS project, since the owner plans to lease or sell all residential, office and retail premises. Is that correct?

Many thanks in advance!