The broad approach to using Generative AI in K-12 schooling focuses on identifying risks and productivity gains rather than the more complex issues of transformational change. As a response, this study examined how school leaders considered Gen AI transformation within their disciplines. Ten subject leaders were interviewed about their pedagogical beliefs for Gen AI. A belief framework underpinned this study to examine more deeply teachers' multidimensional belief systems that direct transformative Gen AI practices in their classroom. The findings indicate that subversive beliefs about Gen AI limit and influence classroom practice; productivity had little influence on pedagogical roles for Gen AI; and each teacher evidenced a different belief system that represented inter-relationships between risk, productivity and transformation which informed discipline-specific classroom Gen AI approaches. This study contributes teachers' pedagogical belief systems for Gen AI use and pedagogical approaches to Gen AI on a continuum towards transformative practice.