Windows 7 and higher offers something that is called a "library". By placing multiple folders in a library, they become one huge collection. Any subfolder will be listed as if they all were in the same folder.
The biggest advantage of this is that if you have 10 folders with lots of subfolders and you place them all in the same library collection, you can then sort by name and have it all sorted correctly.
I know you mentioned you don't want library conf, but someone else posted this and as I was typing it, that one got closed and it seems a proper answer, so I'm posting it here so they can follow here.