A method, apparatus, and article of manufacture provide the ability to integrate multiple engineering design systems in a computer aided design (CAD) system. A design generator is displayed and used to create an engineering design that has different worksheets. Each worksheet represents a different aspect of the design, has local design objects that represent functional aspects of a component that are independent from the component's physical representation, and relation objects that models constraints for properties of the design objects. The objects are organized into a functional layout document (FLD) that is stored in a data center/database that is shared by the worksheets. The FLD is then used to design an engineering design/model.