So, I think that got through what I would call the 'cohabitation' problem:
0) Leave the old version of MCUXpresso alone. Probably best to close it.
1) Download the 2.14 SDK, making sure to select the option for MCUXpresso during generation.
2) Make a folder of your choice like ...\mcuxpresso\SDK_2.14\SDKPackages
3) Copy the SDK ZIP file to that folder and expand all the contents there
4) Open MCUXpresso, and go to Windows->Preferences and burrow down to the following setting. Add the folder in step #2, and bump it to the front of the list.

5) Restart the new version of the MCUXpresso.
Having said that, I could still use some guidance on how to best import the existing MCUXpresso project into version 11.8. I have modified the project heavily to feed the output into IAR. I don't build within MCUXpresso - just use the configuration tools and code generation capabilities to feed into the IAR workflow.
Thanks.