A computer system is provided that enables a designer of a circuit design to fracture and reconstitute a larger design for both computer modeling of the functionality and the physical implementation or rendering of the circuit design. More particularly, the designer may refine or re-work a sub-module of the larger sub-circuit without having to create a corresponding sub-module in the physical implementation. This capability thus avoids the significant complexity required for sub-module refinement in the current state of the art, and provides the designer with a much simpler flow.