Co-production and service user involvement are increasingly encouraged in mental health care research. However, power hierarchies in knowledge can affect the co-production of knowledge by stakeholders. Therefore, the purpose of this article is to deepen our understanding of the relational dynamics at stake in co-researching teams and larger groups of stakeholders involved in research. We reflect on a process of co-production in psychiatric emergency care and show the ethical responsibilities of researchers in dealing with the power dynamics. A collaborative reflection on the process of co-production shows that the voices of service users, who participated as co-researchers, were silenced, thereby reinforcing epistemic injustice. Ethics of care offered guidance for ethical reflection and ways to manage relational dynamics. Instead of ‘fight and flight’, the ‘tend and befriend’ option was fruitful for relational ethically sound co-production, leading to teams and stakeholders jointly reflecting on knowledge co-production. Relational reflexive work brings people together for solidarity, support, and advice.