Here's what I did
Just in case any of you need to do this in the future, here's the easiest way I've found to combine two or more CDP files into one.
Re-save each CDP file as a wave image. You end up with a wav file that has all the edits, fades, etc applied.
Use the new wav files to create a new project file and place your track IDs.
It would be nice to have a small utility that will combine them leaving the IDs intact. If anyone comes across one or has a better way of doing this, I'd like to hear about it.