Best Practice for Creating a New WebHelp Project from an Existing One

I'm currently working in WebHelp Pro (RH version is 9.0.2.271).

I have a WebHelp project which currently supports the 2012 version of one of our projects. What I needed to do was to create a separate 2013 project, using the 2012 files as the starting point. I couldn't find a way in RH to create a new project by importing an existing WebHelp project, so I copied the 2012 files to a new directory, opened up the project, and renamed it.

What prompts this question is that following this exercise, all seemed well, for a time. However, I have recently had to create new topics in the 2012 version. However, when I imported these topics to the 2013 project and compiled, they vanished--although the htm files still appear in the appropriate 2013 file folder (when viewed with Windows Explorer).

After reading some forum postings, I thought that I might have corrupted my database by improperly creating the new project--but if what I did is the wrong way to go about it, I'm not sure what the correct way is. I will be grateful for any suggestions.