So if In get it right, when we post a song in athread where that song isn't indicated bybthe ythhread title (it's come up in the course of conversation drift maybe), we should add "Add" to the subject line of that particular post.

Sounds easy enough. And if someone else has posted the song, is it helpful to do the same to a subsequent post, with a pointer to the earlier one?

Middlewich isn't a good example of bad practice in subject headings, because so far as I can see there is only one Middlewich and that's in Cheshire, England, and Google shows it up in a moment - and seems to indicate that the canal boat festival as the main thing that happens there. But there are plenty of other examples where an indication of country is helpful - names like Boston, Cambridge, Newark, Washington. Or even county - eg Newton, Newcastle.