While there has been a recent interest in trauma-informed design approaches, there is still a need for further research on its use in participatory design (PD). This paper discusses the methodology of a values-driven, trauma-informed PD project which explored how social care records could be redesigned to meet the needs and aspirations of young people (YP). Care-experienced people have often lived through traumatic experiences closely associated with their experiences of care, resulting in a lack of trust in social care professionals. While foregrounding the views of care-experienced people, this project also engaged with professionals, revealing systemic tensions which needed to be navigated through the approach. We discuss application of the trauma-informed methodology and tensions that arose. Our work demonstrates how trauma-informed values and methods can be used during participatory research where groups may have conflicting goals, and how this can enrich the design process.