Is it possible to have symbolic link x point to two or more locations on disk? For example

/home/jo/symbolic link

points to
/var/log & /proc

???

If that was possible, how would the operating system know which file to access?

What exactly are you trying to do? Knowing what you're trying to accomplish would probably be helpful

I want to have the contents of two folders appear in one other folder. I think I'll have to just create a script that will manually create symbolic links from both folders into the 3rd and over-right any pre-existing sl's.

Any other idea's?

Have two links, one for /proc and one for /var/log.

Why would you want to mix up the contents of those two directories like that. What happens if there is a file in /proc that has the same name as a file in /var/log?

The point that dombrowsky and phil.d.g made is relevant. To illustrate, suppose you have a file named README.txt in /var/log and you also have a totally different file that also happens to be named README.txt in /proc

Now, if the /home/jo/symlink directory contained softlinks to all files in both directories, how would the system handle the fact that the "README.txt" softlink needs to simultaneously point to two different files in two different directories? Similarly, if you tried to open "README.txt", would you be reading the contents of the file in /var/log, or the file in /proc? As they have stated before, I also would recommend using two sets of links.