["Health Expectations, Volume 29, Issue 4, August 2026. ", "\nABSTRACT\n\nIntroduction\nInvolving patients and the public in healthcare research, development and innovation is becoming mandatory. Co‐design is a structured approach to collaboratively investigating and finding solutions to complex problems that brings together relevant actors and interest groups. Including experiences and insights from patients and the public in multi‐actor co‐design processes can help to generate and evaluate solutions to complex problems. While toolkits support co‐design project organisation, little is known about the relational work required when facilitating co‐design workshops, especially in healthcare, where professionals often learn facilitation skills ‘on the job’. Reflective accounts are scarce, despite the complexity and unpredictability of co‐design. Based on reflective conversations between two co‐design workshop facilitators, this article explores co‐design facilitation as relational work and offers a conceptual model to guide reflection.\n\n\nMethods\nAuthors B.H. and K.C. facilitated five co‐design workshops involving people living with chronic pain between September 2023 and January 2024. Within 24 h of each workshop, individual reflective interviews (B.H., n = 5; K.C., n = 5) and dyadic reflective discussions between the two authors (n = 5) about the learning and insights gained from the workshop facilitation were recorded. The average length of the interviews and dyadic discussion was approximately 18 min. The data were automatically transcribed and analysed in a reflexive thematic analysis.\n\n\nResults\nFacilitation required managing unpredictability alongside structural considerations. Three interconnected themes were identified: (1) the planning, evaluation and learning space; (2) the workshop‐holding space, comprising structural, emotional, physical and activation subspaces and (3) the tacit space. We present an overarching theme and conceptual reflection model: ‘Holding complex spaces through relational work’.\n\n\nDiscussion\nFindings show that co‐design facilitation is demanding relational work that involves continuous interpretation and awareness. The conceptual model provides a flexible reflective tool for understanding facilitation complexity, rather than a procedural guide.\n\n\nConclusion\nThis case study shows that co‐design facilitators must hold complex, unpredictable relational spaces. While toolkits offer useful structure, facilitation hinges on navigating relational dynamics. Our conceptual reflection model provides a flexible way to understand this complexity through interconnected spaces and to support reflective skill development. Developed in chronic pain contexts, the model may be transferable to other healthcare settings; future work should examine its value for facilitator training in co‐design.\n\n\nPatient or Public Contribution\nTwo patient representatives are co‐authors of this publication and provided critical input on the findings and their interpretation. Both have been co‐researchers in the reported co‐design project since its inception and contributed throughout study planning, workshop delivery, the reflective analysis and reporting of results in the current study.\n"]