Originally Posted by Toxaris
The problem with merging is that every book has a different layout and usually stylesheets. That makes them very difficult to merge, especially automatically.
Actually, that shouldn't be a problem, because the stylesheets can be kept separate. All files can be kept separate with a directory structure like this:
Text files in Book1/text would link CSS files in Book1/css, while text files in Book2/text would link CSS files in Book2/css.
It's merging the OPF and NCX files that can be more problematic, but it should be possible to do something about that too.
Of course, a "seamless" merge, where it is not obvious that there were originally several books and all styles and filenames are unified is much more difficult (aka virtually impossible) to automate.