Configurable process models are recently gaining momentum as a basis for process design by reuse. Such models are designed in a generic manner to group common and variable parts of similar processes. Since these processes are usually large and complex, their configuration becomes manifestly a difficult task. This is why, an increasing attention is being paid to help achieving the process models configuration in a correct and domain-compliant manner. In this work, we propose an Event-B based formal approach that guides the process analyst to easily derive correct process variants while considering business domain constraints provided by configuration guidelines. To show the effectiveness of our approach, we conduct experiments on a case study