Double click on any listed Collection or select one and use the Edit button.

As said, Collections are Criteria based, thus you can't add individual files, only files that match the Criteria of the Collection will be part of that Collection. You can use most tags and you have the Custom Tags to be able to manage what is added to any given Collection. You can use multiple Criteria as well.

Only Playlists can have Drag & Drop of individual files, Collections and AutoPlaylists are Criteria not files based, thus they can't. Collections, however, can have Playlist as Criteria, so you could use a Playlist for Drag & Drop and then have a Collection set to use it.

Thanks Lowlander,
firstly how do you edit criteria, if I go to file>manage collections I cant see where to go next.

Filtering by path would be useful for some collections, but I want to be able to have some collections which are mixed with no specific path, genre, year artist etc

Also, is it possible to build a collection of tunes by something along the lines of drag & Drop or similar?

Thank you
Karl

Collections use Criteria to determine which files in the Library will be in that Collection (so it doesn't depend on which Collection is active when scanning files). You can edit these Criteria under File > Manage Collections by editing the Collection. Criteria like Path are available, but also Genre and others.

Windows 10 pro MM Gold 4.1.28.1905 Files all on a NAS, I have only music from CD's, so no videos, podcasts, downloads etc. I use MM for sorting & tagging only, not playing.

So I'm trying to build up a set of tabs which contain diffrent music collections, with some tunes under more than one tab.
I select file>manage collections>media tree> and create a new tab, say 'Classical'
With that tab open, I scan just the Classical folder on my drive.
There are some pieces of music in that folder that I don't want under the 'Classical' tab, so right click>remove> then the choice 'Delete frome library' or 'Delete from library & computer'
If I select 'Delete from library', it dissapears from all tabs that contain that tune, and I assume if I select 'Delete from library & computer' it will delete the actual file ~ I've never done that BTW

All I want is to have several tabs, each with a collection of music of my choosing under each one, where there may be the same tune in more than one tab.

I have looked here & on the wider net and can't seem to find any answer
Help please! Thank you