Furthermore...
Files like: folder.jpg, [back].jpg, [LP Front].jpg, album review.txt, etc. are ALBUM-related
Files like: bios.txt, [Artist Photos], Discography.html, Artist URL, etc. are ARTIST-related
Each ARTIST and ALBUM should be a Unit/Group/SeparateDatabase (call it as you wish) and there should be a way to easily attach ANY file to any item of this, currently non-existing, but a must-be-developed Artist\Album tree-structure. By adding this separate Databases there will be never questions about file attendants. Waiting when JRiver will start working on MC12.
Currently there's 2 solutions:
1. Import, fill all Artist/Album-related tags and then use a Rename Files Template to move files to correct folder and then Artist/Album-related tags should be changed for all files of that particular Artist/Album.
The advantage of importing files, is that you will see the quantity and contents of all Artist/Album-related attendant files inside Library.
If you will want to view All files of that Artist/Album you should use Locate>Album (except if you are browsing by Albums).
2. Move files to the Album-folder and then if needed to rename Artist/Album-related folders, that should be done only in MediaCenter
If you will want to view All files of that Artist/Album you should use Locate>OnDisk or SendTo>External>...