Views have long been used as a means to structure and manage conceptual models. Model management aims to keep track of the relationships between a set of views as they evolve, and to describe the manipulations performed over them in terms of a set of predefined operators. A major challenge in model management is handling the incompleteness and inconsistency of views. In this extended abstract, we describe a general framework for the management of incomplete and inconsistent views. We use our framework as a basis for exploring the systematic application of important design principles, such as traceability, reusability and separation of concerns, in model management.