Work of engineers is moving into virtual spaces in these days. High number of highly interconnected engineering objects such as parts, structural details, analysis results, manufacturing processes, and equipment control programs are modeled in virtual systems. One of the main benefits of this virtual style of engineering is flexibility of product development. Flexibility is supported among others by free definition of associative connections between modeled product objects and their attributes. However, high number of unorganized associative relations is hard to survey because verification a changed attribute of a modeled object needs an additional survey of affected objects. The authors recognized this problem as one of the most important ones in application of powerful and expensive industrial modeling systems. They propose change management methodology for the application at the construction of large and complex product models. Consequences of change of a product object are checked in its change affect zone (CAZ). This work is intended as a contribution to effective product modeling in product lifecycle management (PLM) systems. This paper discusses the problem of change management in product modeling and cites some relevant works. Next, an approach to management of changes is introduced. Then methodology of change management is explained including knowledge and communication related issues. Finally, implementation of the proposed change management in PLM systems is conceptualized.