There are several different options you have to merge PDF files. How one would do it within Excel is something I can't say is possible or not possible at this moment. But due to the proprietary format of PDF files, it's not that easy to edit or merge them unless you purchase other software. These packages range from $30 to $100's. I'm sure there are free utilities but I always stay away from free stuff on the Internet because it's almost certainly spyware.
Now, there are some utilities which run on *nix OS and they are true Open Source programs which are free and also free of spyware. How you would interface these with Excel...again, I'd have to play around with it and even then I can't say it would work. But long ago, when I was working with PDF files I discovered that a PDF file converted to a true PS (postscript) file, is just a text file. And I found it very easy to merge text files with just about anything. This may not produce the most efficient method of doing it but it sure beat spending $100's on Adobe's Acrobat software.
I can also recommend another software called Revu by Bluebeam Software http://www.bluebeam.com. This is an expensive option that has more power than you could imagine when working with PDF files.
But to be completely honest with you...I can't say there is a magic bridge between Excel and PDF files. Someone may reply shortly and completely prove that wrong. Remember, there is always someone out there more clever than yourself. And forums like this are where you find clever ideas from others.
One of those *nix utilities is available at http://www.pdflabs.com/tools/pdftk-the-pdf-toolkit/. It's a command line program so you could theoretically shell to DOS and run it to merge PDF files. I have used it before to install watermarks, merge...etc with PDF files and it's pretty good...plus it's free.
Bookmarks