This article aims to investigate how participatory design influences interdisciplinary relationships in digital heritage projects. In particular, the article reflects on opportunities and challenges of interdisciplinary encounters in participatory design, with the cross-border project “Terra Mosana” as a case study, which aims to investigate, digitalize, and communicate the shared heritage of the Meuse–Rhine Euregion (EMR). Terra Mosana is a collaboration between multiple partners from municipalities, museums, cultural heritage sites, and universities in different EMR cities. Partners of the project have different backgrounds that vary from archaeologists, historians, and heritage professionals to computer scientists, developers, and communication specialists. My role in this project focused on designing and organizing several participatory design workshops with citizens of the EMR, aiming to empower and enable them to share their views about their shared history, and what they want from museums and other cultural institutions. Those workshops play a crucial role in the project by creating meaningful connections across the different disciplines involved in the project. In this article, I focus on the negotiation processes between the partners involved: What challenges were they confronted with? How did they arrive at creative solutions, and which issues remained unresolved? My analysis does not draw only on my participatory observation of workshops, but also on a focus group discussion that invited the partners to reflect on and assess the collaborative process.