Hi Thom (not Tom). 
- As it is not really part of the title, it better suits the disambiguation comment, indeed.
- It should follow ETI style guideline
(« deluxe/legacy/expanded edition », in lower case)
(except proper nouns of course like « UK only edition »). - This disambiguation comment does show up in collections, by the way.
In your example, you would move it as Never Enough Edition → Never Enough edition in the release comment.