How should project teams use the Enterprise Data Model?

How should project teams use the Enterprise Data Model?

There is a team of data architects that have been working on a logical enterprise data model (EDM) for three months, and the EDM is estimated to be 40% complete. Many projects are underway that can benefit from the EDM, yet the architects are divided as to how project teams should use the EDM. Some prefer Approach A while some prefer Approach B.

In Approach A, the project modeler meets with the EDM architect and together they decide on the subset of the EDM that is relevant for the project. Then the project modeler uses this subset as a starting point for their logical data model (LDM) and extends this model to meet the project requirements. The architect then reviews this project LDM and reconciles it back to the EDM. Once the architect approves the project LDM, the physical data model (PDM) could then be built.

In Approach B, the project modeler meets with the EDM architect and together they extend the EDM to contain the project requirements, and then the project data modeler uses this EDM subset as the starting point for the project PDM.

Which is the better approach and why?