Virtual evaluation of complex command and control concepts demands the use of heterogeneous simulation environments. Development challenges include how to integrate multiple simulation engines with varying semantics and how to integrate simulation models and manage the complex interactions between them. While existing simulation frameworks may provide many of the required run-time services needed to coordinate among multiple simulation engines, they lack an overarching integration approach that connects and relates the interoperability of heterogeneous domain models and their interactions. This paper outlines some of the challenges encountered in developing a command and control simulation environment and discusses our use of the Generic Modeling Environment tool suite to create a model-based integration approach that allows for rapid synthesis of complex high-level architecture-based simulation environments.