This research paper examines the implementation and impact of customised roles in large-scale agile software development teams, specifically within the Scrum framework. This is a single case study based on 15 practitioners’ interviews from a Swedish software company to review the dynamics of role customisation. The two customised roles of Product Guardians and Security Masters are crucial for addressing complex secure software development, maintaining product quality and security, and fostering team self-organisation. The study also uncovers challenges associated with role customisation, such as the potential overburdening of individuals and disruption of self-organisation. The findings contribute to the discourse on agile methods' adaptability and provide practical insights for organisations considering similar role customisations. Furthermore, the research opens the door for future exploration of organization-wide roles that promote self-organisation.