Hi SoilnRock
Just registered here because I also wanted to change the display of files in-between folders as you ask in your question. Back then (couple of weeks ago, I'm still a newbie ) I also found the solution in the thread herojoker pointed out.
That title format string will place a certain unicode character in front of the mp3 files (something like a bullet I guess) and there for foobar sorts them after the folders (roughly spoken).
From some other sources I was able to build my own custom title format display, which also solves the sorting problem with the files.
I also needed some string that would let me see three base-folders, that I added to my library (one folder on my harddrive and two folders on my external). So I am not sure if the following is helpful for you, well - anyway, here it is
$replace($replace($directory_path(%path%),C:\Long_Path_To_Harddrive_Folder,Harddrive,
Long_path_externalHD_1,external_HD1,Long_path_externalHD_2,external_HD2,),\,| )|$char(8250) %filename_ext%
What it does is, it replaces those three long paths from the library and replaces them with the words right behind each long path. You can add as many replace "pairs" as you like, and you can also delete some.
In addition to the replacement this also adds said unicode characters right in front of every single mp3 file (the one I used is some kind of angle bracket; you have to try some out because I also found that some chars are difficult for foobar to process and the display is very slow. If you have any more questions as to how to add the custom string to album list or how to modify it, I'll try my best to answer