[TimW]

The way I usually handle this is to import the HEC-2 sections into one geometry and your cross sections cut from the LiDAR into another. Make a list that details which HEC-2 cross section corresponds to each of your new cross sections. Add the channel data into the new cross sections using the "Graphical Cross Section Editor" tool (check the boxes for "Compare Geometry Files" and "Merge Cross Sections," and select your HEC-2 import geometry as the comparison geometry).

If you are submitting to FEMA you may want to re-name your new cross sections to have the same stations as the current effective model. In any case, FEMA will want to know how the elevations compare, which is where your list comes in handy.

I would be interested to know if anyone else has a better approach.