Advances in smart devices and networks are enabling convergence between systems of systems and cyber-physical systems in which computing elements interact closely with the physical environment. The development and maintenance of such systems should be inherently collaborative, crossing boundaries of constituent system ownership as well as semantic differences between engineering notations and disciplines. We present instances of model-based methods and tools that aim to bridge these gaps. Using a case study from smart grid control, we discuss the challenges in realising collaborative systems of systems that merit the reliance placed on them.