This study examines an urban middle school teacher design team's capacity for creating integrated science, technology, engineering, and mathematics curricula. Using Brown's pedagogical design capacity (PDC) theory, which highlights interactions between personal and curricular resources, this paper introduces an extended framework that includes social interactions as key influences on teachers' design abilities. Findings show that individual teachers' spontaneous curriculum modifications were adopted by the team, becoming collective resources for ongoing redesign and improving their design capacity. Teachers effectively used each other as resources to address unexpected challenges in integrating science, engineering, and mathematics concepts. Three types of social interactions were identified as collaborative resources: (i) Storytelling: sharing experiences to make abstract concepts actionable for curriculum development; (ii) Protocols: structured methods to address curricular problems related to integration; and (iii) Assessment "for" curriculum redesign: using assessment tools to inform and improve the curriculum. The Collective Design Capacity for Enactment framework is introduced to describe PDC within a social context, highlighting the importance of social interactions in bridging curriculum use and development, thus extending the literature on PDC.