This research aims at accompanying farmers in building a durable collective management of their subsidence cereals varietal diversity. Varietal diversity dynamics are driven by farmers' individual choices and strategies on the one hand, and by the seed system functioning on the other hand. We think that the mutual understanding of the interactions arising in this complex system is a prerequisite to work together on the construction of durable collective management rules. We follow a dynamic research process that uses models building and simulation through Agent-Based Models and Role-Playing Games. We have used these tools to collect, synthesize, formalize and exchange researchers and stakeholders knowledge. As a result, we have a model of the system built with the active input of Malian farmers. This model will next be used in simulations for collective prospecting on management scenarios.