Companies collaborating to develop new products need to implement an effective management of their design processes (DPs). Unfortunately, PLM systems dedicated to support design activities are not efficient as it might be expected. DPs are changing, emergent and non deterministic whereas PLM systems based on workflow technology don't support process flexibility. So, needs in terms of flexibility are necessary to facilitate the coupling with the environment reality. Furthermore, service oriented approaches (SOA) ensure a certain flexibility and adaptability of composed solutions. Systems based on SOA have the ability to inherently being evolvable. This paper proposes an SOA based approach to deal with DP flexibility in PLM systems. To achieve this flexibility, the proposed approach contains three stages. In this paper we focus on the first stage identification.