Let's say you have a single project of 500 Topics with about 300 graphics. It may be starting to get a bit unwieldy, too big and slow? You might decide to split it into smaller help files and then join them together. In Help Authoring, this is called Merging.
One of the main benefits of merging is that you can modularize your help files. A classic example is an accounts program that has a help file for Invoicing, Sales etc. Your customers may purchase two out of three modules, so you only send them two help files. But then they could later buy the third module. In that case you need only send the third help file and because the three help files were originally merged, the third help file is automatically read in and accepted by the existing help files.
Choose your Master!
In order to achieve this, you need to designate a single project as your Master help file, then merge all the others with it. There are several steps to complete depending on whether you are merging WinHelp or HtmlHelp. But essentially, you list the files that will be merged, then in your Master project's contents, you include the contents of each of the other help files. Confused? Don't worry, this help file will lead you through it step by step in a moment.
Drawbacks of Merging
It's a little bit complex, and you need to maintain each project so that you don't get duplicate context strings or HelpID's. Also, if you are referencing your help file from an external application then you need to know the help file name and HelpID specific to each help file. This can be cumbersome. Also Browse Sequences in your Nonscroll region are Project specific, so they won't naturally continue to the next merged Project, but this may be how you would prefer it.