In recent years, there has been an increase in the integration of socioscientific issues (SSI) into educational practices, which are recognized for enhancing higher-order thinking, scientific literacy, ethical considerations, and civic engagement. SSI teaching equips students to tackle global challenges, although they are complex challenges for in-service teachers. Addressing the need for professional knowledge and skills in SSI teaching is vital for meeting future societal demands. Studies have shown that engaging teachers in co-design practices within teaching communities enhances their SSI teaching proficiency, yet empirical evidence supporting these collaborative interactions is limited. This study investigates the professional learning of five in-service teachers involved in community activities, focusing on their development of SSI-based lesson plans. Through convenience sampling, participants' lesson plans and discourse relevant to SSI teaching were analyzed using descriptive analysis, epistemic network analysis (ENA), and context analysis. Results indicated that these plans incorporated essential SSI teaching elements, and discourse during community activities fostered epistemic frames conducive to SSI teaching. Reflective discourse notably enhanced both implicit and explicit aspects of these frames, with teachers' identity development significantly shaped by practical experiences. These findings suggest that practical engagement in professional communities may effectively foster teachers' SSI teaching skills, offering insights for crafting professional development programs in SSI education.