The objective of this exploratory study is to add to our understanding of ongoing product design decision-making to reduce eventual decision-making bias. Six research questions are formulated with the aim to establish if and how functional membership and informal patterns of communication within an organization influence whether and why employees are willing to engage in product design modifications. We selected as a field site for our study an industrial company that had an internal research and product development operations and where the employees were located on the same site. A three-step approach within the manufacturing case company was designed: (1) In-depth interviews were carried out with managers and employees; (2) a survey questionnaire was sent out to all employees involved with a specific product that is subject to potential design modifications; and (3) a post hoc group feedback session was organized to further discuss our findings with the management. First, analysis of the nine in-depth interviews establishes a taxonomy of product design decisions involving four types of criteria; product-related, service-related, market-related, and feasibility-related criteria explain why employees would engage or not in product design modifications. Second, it is demonstrated that functional membership has a significant influence on the concern for these decision-making criteria as well as on the decision to proceed or not with product design modifications. In other words, functional membership influences whether and why employees are more or less willing to make product design modifications. In this manufacturing company, a global industrial player, the differences in concern appear especially for service- and market-related criteria and pertain particularly to the research and development (R&D) and service function. Overall, even though the perceived performance of the specific product under study did not differ significantly among the different departments, it is observed that R&D employees were significantly less in favor of proceeding with product design modifications than other employees were. Third, using UCINET VI software, we provide some explanations for this finding. It is shown that informal patterns of communication (i.e., employee degree centrality) operate a situational opportunity to make modifications to an existing product and a cognitive opportunity influencing the decision to modify product design following an inverted U-shaped function. Ultimately, we derive practical guidelines for an ideal product–team composition to reduce product design decision-making bias.