Individual complex systems routinely operate with other complex systems (in a complex environment no less!) to achieve desired military capabilities; generally speaking, Lethality, Mobility and Survivability. While challenging in itself, this scenario is complicated by the fact that new systems are being deployed and retired which imposes training requirements and adaptation on the part of users and maintainers. The author will characterize the challenge and describe an approach to coping with the challenge and mitigating its impact. Specifically, ground combat vehicle capabilities are undergoing a transformation which can be accelerated by employing some of the techniques described and improve our soldiers’ ability to meet and defeat rapidly changing threats. The technique is generically referred to as Capability Planning and it is supported by set of software tools and analytic techniques, commonly called a Decision Support Framework. This paper characterizes the techniques and generally demonstrates how engineers can better collaborate with program managers and customers though their use. Several examples of successful implementations will be described and clearly demonstrate the potential for the rapid fielding of increasingly effective military capabilities by interoperable complex systems, enabled by the use of these innovative engineering applications. This paper focuses on communications systems that enable Command and Control functions which are seen as key enablers for military capabilities such as lethality and survivability. The conclusions, however, generally apply to any systems that must interoperate.