Defining the ownership of rental housing can be a difficult task. In recent years there has been an increasing obscurity of ownership in administrative records as more property owners use Limited Liability Companies (LLCs) on deeds and in tax assessment records. In many cases, this obscures the nature and scale of ownership and makes research into property ownership, investors, and landlords more challenging. To overcome these challenges, we compare different text-matching methods within property tax assessment records in Boston, MA from 2004-2019. We show that the source of the difficulty in creating an accurate knowledge of landlords and their portfolios of properties has shifted in the past decade from the scale of data and the messy nature of administrative data to an intentional strategy of obscurity through LLCs. To do so, we incorporate linking to corporate records to uncover intentional ownership obscurity. We assess the prevalence of obscurity among landlords as well as the extent to which it is undermining our ability to observe patterns in rental housing in ways that cannot be accounted for solely with text-matching. These include how obscurity hides not only an increasing consolidation of property ownership in the past decade, but also concentrations of disorder and evictions. In doing so, we demonstrate a comprehensive method for uncovering this obscurity and show how this representation of property ownership can form the basis for understanding inequities in rental housing and the effects of property consolidation.