With the information you have provided, the following should work:
1. Make a smartlist that uses the following rule:
[media type]=audio ~dup=[album],[filename (path)]This should return all tracks that share the same album, and have all album tracks in the same folders.
2. Make another smartlist using the following rule:
[media type]=audio playlist is not any the playlist you made in step 1You will need to use the wizard for this smartlist rule in order to get the playlist exclusion correctly. This should give you the files you are looking for. ie. all files that share the same album but are stored in different locations.
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Once you have identified albums such as your "Now 31" album, select the files and set the [album artist] field for those tracks to
(Multiple Artists) (with the brackets) and then, when you use the rename move and copy files tool to correct the file paths, it will correctly treat them as multiple artist albums and file them under "Assorted"
This thread, while old, still applies today and should help you to understand the advice offered above.
If any of the steps are unclear, or if you have any other questions, just shout.
-marko