Complex software intensive simulation systems must respond to changing technology, environments, and requirements. Hence, dynamic extensibility and adaptability is a significant concern in an application domain. However, existing interoperability and composability solutions are limited in dealing with (1) dynamically evolving content needs of existing simulations and (2) run-time inclusion of new components into a simulation system. Simulations that are dynamically extensible, while being interoperable require principled designs that facilitate engineering extensibility, interoperability, and composability in the first place. We propose and examine the utility of a strategy based on an agent-mediated meta-simulation architecture.