I think I spoke too soon. Here is what I've learned in the last 24 hours:
1. If a project was created using the 44.1k rate set in preferences, all software synths will use that setting.
2. Deleting audio files of one sample rate and replacing them with the new sample rate creates something really unstable since somewhere the original sample rate is written in the file. (ask me how I know,...)
3. I can export the wav files from Sonar into a different format, but there is little guarantee they will time-align when reassembled.
It appears that even a simple midi-only file using soft synths will need to have the tracks copied into a new file with the required sample rate. I was hoping there was a dialogue box somewhere that would let me change the properties of a file so that all synths would magically switch to the new setting.
I will try to use the time-stretch feature to align exported files to the video file.
Thanks for the input.