This study focuses on how knowledge sharing across boundaries of merging entities during an information system (IS) implementation project in a shared services center (SSC) context affects the resulting system functionality. Although the literature stresses the growing adoption of the SSC as an outsourcing model, there is a lack of studies that examine shared services as a dynamic process of knowledge sharing across the organizational boundaries. We draw on a sociomaterial practice perspective and on the theory of workarounds to analyze an IS implementation project in a healthcare organization resulting from a merger of previously independent hospitals. The results suggest that new technology can be enacted in different ways as it links up with practices of different communities of users. We propose a multilevel process model that indicates at the end of the project a resulting mix of formal and informal (workarounds) practices that emerged from a dialectic process of resistance to, and negotiation of, the IS configuration during its implementation.