Today's training simulations are only marginally able to address emerging operational requirements. Operations other than war, small unit operations, and countering weapons of mass destruction are a few examples of training challenges facing our forces. Unfortunately, wholesale rework of legacy models to look at new requirements is too time-consuming and expensive and usually requires new hardware platforms. Recent funding cuts from the Services' modeling and simulation budgets are further exacerbating the problem. This paper describes the integration of adjunct models with legacy models to provide an evolutionary approach to address emerging training requirements. The Army's Corps Battle Simulation (CBS) is used as an example to explain the concept and highlight the recent integration of an adjunct model to address battle drill for ballistic missile threats.