System of Systems (SoS) engineering is a challenging research direction because an SoS has distinctive characteristics in comparison to distributed systems. UPMD and SysML provide adequate frameworks and notations which help in the process of modeling and architecting SoS. Projects such as DANSE and COMPASS have selected the most relevant views among the numerous views of UPDM. By nature, an SoS evolves after its initial deployment. To deal with evolutions, the architect needs to model configurations, what was not considered in previous state of the art. Modeling configuration is indeed key before we can model the evolution itself. In this paper, our contribution is a new modeling process, based on UPDM and SysML, that helps the architect in designing the configuration of an SoS. The proposed process is illustrated with the case study of the French emergency service.