You can create an unlimited number of playlists when you subscribe to a music plan through ShootProof. You'll add songs to each playlist, and then assign a playlist to each gallery.
To create a playlist:
1. Go to Photos > Music > Playlists > Add New Playlist
2. Name your playlist
To add songs to a playlist:
1. Go to Photos > Music > Songs
2. Click the "Add to Playlist" button beside the song you'd like to add
3. Choose the Playlist
To assign a playlist to a gallery:
1. Go to Photos > Galleries
2. Click on the specific gallery to which you'd like to add music
3. Go to Settings > Gallery
4. Choose a Playlist, and save!