Medium-sized production service providers have production performances, which can combined with services, like distribution or development processes, available for their customers. This business model comes to specific challenges in production planning and control. In particular for overcoming the uncertainties of determination the primary requirements, appropriate methods are needed. In this article the conceptual structure and the aspects of application of a simulation-based assistance system, which enables systematic and valid evaluation, selection and also configuration of this methods, are described. At that point, specific system requirements, like the development of a simulation model, which is representative for medium-sized production service providers, and also scenario creation using scenario technique, are considered.