Profound transformations are currently impacting the intricate relationships between human pastoral activities and Alpine mountain ecosystems. In this context, we were invited as human-computer interaction practitioners to join an interdisciplinary team, to reinforce the use of computer simulations in meetings with local stakeholders. However, due to the diverse nature of stakeholders involved and their interactions, the specific format of these meetings and the utilization of model simulations remained unclear. To clarify these uncertainties, we designed a cards-based ideation method to collectively plan participatory workshops and envisage if and how information technology tools could be integrated. In this paper, we present the design of our ideation method Cards4Concertation and two workshops that implemented it. We then reflect on our findings with lessons learnt both for designing cards-based activities for ideation within interdisciplinary teams, as well as visualizations for participatory planning and decision-making.