Product design activity is traditionally presented as a succession of four to six stages. In the early stages of design, during the search for concepts, multi-disciplinary teams are working together, sometimes on the fringe of the digital design chain. But it is during these stages, that most of the product development cost is committed. Therefore, collaboration should be emphasized, and PLM software should contribute to it strongly. This paper first defines the boundaries of the early stages of design. Then, we analyze designer collaboration in this stage and describe the knowledge necessary for efficient collaboration. Finally, we propose and test a concept for a tool to assist the early stages of design, to be integrated in a continuum with other existing digital design tools. A case study is presented in Verallia, specialized in the design and manufacturing of glassware.