I tried a symbolic link with the wordlist.ini file, and it did not work. Scrivener refused to recognize the file after it was changed on another machine and instead erased everything and created a new file.
What did work was a hard link, which seems to be frequently confused with a symbolic link (I was confused). From the command line, the mklink command with no switches creates a symbolic link, while mklink with the “/h” switch (mklink /h) produces a hard link, and that appears to work.
To create the link, i have a text file with the .bat extension. I have two commands in the text file:
del C:\Users[username]\AppData\Local\Scrivener\Scrivener\wordlists.ini
mklink /h C:\Users[username]\AppData\Local\Scrivener\Scrivener\wordlists.ini [Path to the folder containing the file in Dropbox]\wordlists.ini
To create the hard link I run the bat file, but as an administrator. That is important (right click, select Run As Administrator).
The del command will delete the existing file, so if you have a lot already in the file, move it over to the target folder in your Dropbox first.