Through a longitudinal, qualitative study, we explore how preexisting embedded relationships shape boundary-spanning actions in the postacquisition integration process. We examine the role of union representatives in the integration process and find that in our case, they are significant boundary spanners. They share knowledge, promote the acquisition, and mitigate conflicts both within and between the merging organizations. Their intra- and interorganizational preacquisition relationships are the contingencies for their boundary-spanning actions. Our study makes several contributions to the literature. First, we show how a set of actors, mostly ignored by the mergers and acquisitions literature, can play a key facilitating role in the integration process. Second, we extend the understanding of the autonomy-integration dilemma in the postacquisition integration literature by conceptualizing preexisting relationships as precursors to postacquisition boundary spanning. Third, we challenge the classical conception of relational inertia as a path-dependent hindrance by showing that preexisting relationships can be leveraged to facilitate postacquisition integration. Finally, we contribute to the boundary-spanning literature by identifying the nature of embedded preacquisition relationships as an important contingency to boundary-spanning actions in interorganizational encounters.