This protocol describes a research and development (R&D) project aimed at optimizing a targeted, preventive, efficacious, and tailored intervention called Supportive Parents Coping Kids (SPARCK). Combining recent developments in basic and intervention research, the goal of this project is to develop, test and optimize a unified parent training intervention targeting children who display externalizing and internalizing symptoms and parents who are at risk of exhibiting maladaptive or neglectful parenting behaviors. We plan to utilize various design-based research methodologies to investigate what works for whom in which context, points which are essential to the innovation process, by employing a mixed methods research design and an iterative optimization process of testing and refinement. Furthermore, we introduce a cocreation process for SPARCK to involve relevant stakeholders working in Norwegian frontline services for children and their families to ensure that the intervention adheres to the needs and constraints encountered by these stakeholders and thereby promote the scalability and sustainable implementation of SPARCK. In this paper, we present the theoretical and methodological background of this approach to R&D in the field of mental health prevention as well as the operationalization of innovative methodology in the current project. This R&D approach aims to produce new knowledge concerning individual change mechanisms in parent training interventions and stakeholder feedback pertaining to intervention components and implementation strategies, all of which are imperative for the iterative SPARCK design process.