Adding a group really isn't that hard once you get used to it.
The first thing you want to do is go in your main Feralheart folder on the C drive. (Or if you keep it somewhere else, go there.)
There will be a file called 'music.cfg'. Open that up with wordpad.
Now you should see a list that looks similar to this one. (You'll most likely have different music than mine.)
[Title]
media/music/title.wav
[Plains]
media/music/Plains.mp3
[Caves]
media/music/Caves.mp3
[Sacred]
media/music/Sacred.mp3
Create a new section somewhere under the four titles that follows this format:
[Map Music]
media/music/track1.mp3
media/music/track2.mp3
media/music/track3.mp3
* You obviously change what the name of the tracks are and perhaps the title if you want and add as much music as you want. But don't mess with the directory.
** For some reason, Feralheart gives a staticy sound when switching between tracks for .mp3 files. It is recommended that you convert them to .wav as they do not do this. But this is completely optional.
Make sure that you save the changes and all the music tracks you want for the map are in the music folder and not the sound folder. You can switch it if you really want to but its easier to keep it in that folder.
Now all you do is open up map maker, input the name of the music group you want in the bar below and presto! It should all work. Make sure when you export the map if you are going to share it with others that you give them the same music.cfg or at least the code to add it in.
Hope this helped and good luck with the map making. ^^