This article focuses on the learning activities provided for ten experienced teacher educators from six teacher education institutions in Ukraine. The authors examine how teacher educators approach professional development when introducing a new interdisciplinary course in teacher education programmes Methods of Teaching the interdisciplinary course "I Explore the World." The study stresses the importance of sustained support for professional learning. It uses Action Research to better understand the professional development process, drawing on various action research models, including Riel's model. Our results suggest that open-mindedness and readiness for change are vital for professional growth for teacher educators when encountering such a significant reform. In addition, the results disclose that the interaction within the framework of the international project is influential for the professional growth of teacher educators' curriculum developers. It stimulates a change in their thinking and allows them to see professional issues from another angle.