Your best bet and the easiest way to maintain this would be to create a Website Project in the HTML Editor. Use whatever local directory you plan to use for the site and then copy whatever pages you need to that directory (do the copy and paste outside of the HTML Editor) and then use the refresh button in the HTML Editor tree area to make sure all the pages are showing.
The thing about the editor is that it's just like any other text editor like Notepad. It will only open what you tell it to, it doesn't instinctively have any memory of where things are located on your computer UNLESS you setup a Website Project. It will then open that location when you choose that project in the pull down menu list for them.
Put all the files you want to use for that website into that directory, arrange them how you want them and the project will then show it that way and you will have much easier access to it. Do this for each separate project you will be working on.