3D Model for Milling & Resurfacing

I am creating a 3D model for an urban, multi-lane widening project for FDOT.  At the beginning and end of the project there is no profile grade required, since I am connecting to the existing pavement by milling (stripping) and resurfacing (overlay).  From Begin to End new pavement construction there is a proposed profile grade.  It seems that there could be at least two methods to create the model.

  1. Use a single corridor with three template drops. The first and third template drops would be for the milling & resurfacing the existing pavement, and the second template drop would be for the new pavement construction.  The problem I’m facing with this method is that in order to place the second template correctly in the 3D model, the Corridor’s active profile must be the proposed profile grade.  But since the profile grade is not applicable to the first and third templates, nothing is drawn for them in the 3D model.  I’ve also tried creating three separate corridors in the same DGN file, but the ORD software doesn’t seem to permit that, either. 
  1. In DGN file #1 create a Corridor for the new pavement construction with a single template drop, and set the proposed profile grade as the active profile to create 3D model #1. In DGN file #2 create a second Corridor for the pavement milling & resurfacing, with two templates drops for the beginning and end of the project, set the existing ground profile along the CL of Construction as the active profile, and use horizontal and vertical Point Controls as needed to create 3D model #2.  Then, reference 3D model #2 into 3D model #1, and ultimately merge the two 3D models together for delivery to the contractor.

Please provide comments and insight on the best approach to model this scenario.