Joining to recent research works for better control of product definition in model space, the authors of this paper developed a novel approach and concept for the methodology of situation based control in contextual object definition. The main purpose of the proposed modeling is improved active knowledge driven definition of product features. In the currently applied industrial product modeling, human defines rule sets and other relationship features as active entities during construction of product model. In order to improve this current technology, the proposed modeling applies human defined and coordinated knowledge for the generation of relationship features establishing a higher level communication surface for humans who define product in model space. Currently applied situation based control of product object definition is completed by adaptive change representation definition of which is human request initiated, situation driven, and knowledge based. New definitions are proposed for situation and knowledge. Process of the situation driven product object control is outlined.