Engineering activities for design, analysis, manufacturing planning, equipment control, product support, recycling, and other product related purposes are moving into highly integrated and model based software systems. This trend is urged by increased application of intricate and styled shapes, high number of product variants, frequent changes of product, complex product structures, short innovation cycles, and collaboration of remote situated engineers. Recent engineering systems have functions for sophisticated modeling. However, they are not capable for tracking effects of changes of engineering objects on other engineering objects. This capability would require high level knowledge based decision assistance where changed parameters are verified or produced. The contribution by the authors to methodology for this type of decision assistance is based on integrated handling of a set of closely related engineering objects. The concept includes extended definition of behavior modeling, tracking of change chains along associative modeled objects, and application of knowledge verified by engineers. This paper starts with an outline of functionality of the proposed extension to industrial engineering systems in order to improved decision assistance. Following this, integrated model object (IMO) is conceptualized as a basis of the proposed extension. IMO approach is compared with present conventional way of product modeling. Next, a new concept called as intent-based behavioral adaptivity (IBA) as an integration of handling of engineering objectives, modification of engineering objects, and application of human intent is explained. Finally, implementation of the extension for lifecycle management of product related engineering (PLM) by one or more IMO through application programming interface (API) is outlined.