The demand of current markets for innovative products with the latest technologies and meeting environmental and sustainable requirements has increased the demand in the product engineering areas within organizations. Furthermore, regardless of the growing complexity involved in the new product development process, delivery/launch times have been increasingly tight. In this context, it is identified that these market/society demands have affected the current development patterns, leading to situations such as input data inaccuracy, incompatibilities between project requirements and engineers’ knowledge, interface errors or output data inconsistency. These and other harmful consequences lead to increased costs, delays in the product development process, and deterioration in the quality of delivered products. Therefore, this research proposes an approach to determine similarity and critical path of functions that help to reduce the time and information inconsistency during the conceptual phase of the complex product development process. The proposed approach contributes to reducing the conceptualization and synthesis time of new products from the application of function similarity and concurrent engineering concepts. Such a method called SuC (Step up Concept) determines the functional groupings and their synthesis complexities. With this, it is possible to identify the critical path that will lead to mitigation actions by the Engineering teams. The proposed method was tested using an experimental case applied to different types of real products, confirming its potential for the development of complex products, as it offers new perspectives in aspects of conceptualization and synthesis in the development of different complex products.