Under current HMDA rules:
2. Property location–multiple properties (home purchase/refinance of home purchase). For a home purchase loan, an institution reports the property taken as security. If an institution takes more than one property as security, the institution reports the location of the property being purchased if there is just one. If the loan is to purchase multiple properties and is secured by multiple properties, the institution reports the location of one of the properties or reports the loan using multiple entries on its HMDA/LAR (with unique identifiers) and allocating the loan amount among the properties.
Under new HMDA rules effective 1/1/18: You report the property that is securing the loan, if multiple properties secure the loan you pick one to report on in a single LAR entry.