Diverse authors defend the idea that stakeholders’ involvement is of crucial importance in most decision-making processes. Adequate selection and involvement of the actors of a given social system is a key issue to increase understanding of the problem, and even to ensure organisations’ viability. This paper is based on a group model-building project conducted with the Netherlands’ Environmental Assessment Agency, to understand how the main actors of the Dutch real estate market affect the dynamics of the mid-range price segment. We illustrate the approach we followed to model stakeholders’ decision-making without including them in the participatory process. The aim of this paper is to analyse the limitations of the chosen approach, but also the extent to which its application is valid to inform public decision-makers. We argue that, modelling stakeholders’ decision-making without them in the room can be a useful approach if the process follows a well designed and executed structure including a consultative and a participatory phase. For the case study, the consultative phase consisted of interviews with the stakeholders, and the participatory one with the GMB intervention. We further emphasise the importance of stakeholder analysis to guarantee that the system boundaries represent the actual policy-making domain of the decision-maker.