I might think it would be easier to simply determine what topics are only part of the Pro version and tag those for exclusion when you create the Express version.
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Yes, I marked the topics that are only part of pro (about a third of the project) and it is working fine. I also discovered that there was a need as well for an express only conditional tag (such as a different screen shot). So, to create the pro version i exclude "express" and to create the express version i exclude "pro". I also set up a variable for the different product names. It is working perfectly fine, thank you.