Is there a way to combine "Favorites"?

The only issues with that are a) that there isn't a directory called Configuration, and b) that carrying out this procedure is likely to lose you any new favorites you've created in the current version, because there's no evidence that I've ever seen that this  merging process works. Indeed, I have a thread where one of the developers says that it doesn't - and nothing's changed since he wrote that; read the last comment in this thread. 

And quite frankly, it is not recommended that you reach out to Adobe support unless you are plain desperate, or it's do do with your CC account. Their normal ploy when confronted with anything they can't answer is to send people here.

So the correct answer is that you have to open the old  Favorites.xml file with your effect in in an .xml editor, select the part you want to copy, open the current one and paste the whole entry into it, and save the result. That should work.