Integrating business and information technology (IT) is essential for enterprises to be competitive. The integration of business and IT forces project teams to analyze and design a hierarchy of systems such as: groups of companies collaborating in business systems, people and IT systems collaborating in business processes, software components collaborating in IT systems, and programming language objects collaborating in software components. The current tools, and in particular MDA, have not been tailored for the design of hierarchical systems. As a result the project teams have difficulties designing integrated business and IT systems. In this paper we present a technique for supporting the design of hierarchical systems. We were inspired by Millers General Theory of Living System, a theory that addresses the analysis of hierarchical living systems. We provide concrete guidelines on how to introduce levels in UML-based system modeling, in general, and in MDA in particular. This allows the project team to develop one, common, integrated enterprise (or project) model. This in turn enables the different specialists to reason about and design business and IT systems that are truly integrated. The overall benefit is an increase in the project success rate.