There have been various proposals for the formalization of appropriate viewpoint-based frameworks. Each of these approaches have been devised with a specific motive and to address an important concern. The model that we pro- pose in this paper attempts to provide a basis for conceptual model integration particularly with the existence of partial ignorance and uncertainty. The model attempts to formal- ize the degree of uncertainty present in experts' expressions, and proposes tools for conceptual model integration and formal consensus building between the involved viewpoints. Metrics for measuring integration effectiveness have also been proposed in this paper. The model proposed in this paper has been employed in a case study to collaboratively develop a conceptual model for the Pet Store application.