In case you're not aware, you can easily insert an audio track and simply copy and paste the clip from a frozen track to it.
To answer your question, and to keep things non destructive, in one song file you could keep everything together and freeze soft synths as desired. Then you could copy that file.
In the copy file you could create blank audio tracks as I mentioned above. Then copy and paste the frozen audio clips to those new audio tracks. Then delete the synths from the synth rack and their associated tracks. You'd then be able to get the file to open for the other person if they had a comparable version of your Sonar.
If not, you could export the whole song as individual wave files for them to import into their own software.