The current European Directive for Flood Risk Management (FRM) requires a demand-driven approach in which policy makers work together with practitioners and the general public in preparation of FRM plans and actions. In that context, the DIANE-CM project, funded by the 2^nd ERANET-CRUE initiative proposes an innovative approach which brings the conventional modelling procedures in a participative environment, where decision-making process are directed towards a consensus among all involved parties, which legitimises the decisions and enhances their successful implementation. The methodology for this aim is supported (amongst other methods) with the implementation of a collaborative platform (CP) for shared understanding of flood risk and the execution of a Collaborative Modelling Exercise (CME). This CME is developed with three modules: Individual profile, group profile and collaboration and negotiation stage. These modules lead towards preferred ranking of proposed alternatives for FRM by individual stakeholders (SHs) and by the group as a whole, which are based on a background technique adapted from the TOPSIS Method (Technique for Order Preference by Similarity to Ideal Solution). This paper presents the main findings and lessons learned from the implementation in two case studies: the River Alster catchment (Germany) and the Cranbrook catchment (UK).