Make "Layers" actual layers

Right now the different options are titled Layers but layers to me indicates being able to stack multiple items together. I see no way to currently play “Crickets: Nighttime Nature's Rhythmic Soundscape” and “Forest Birds Chirp: Dawn Chorus for Calm and Focus” together at the same time even though they would have really great synergy. Or playing “Forest Birds Chirp: Dawn Chorus for Calm and Focus” and “Rosy Horizon Hum: Pink Noise Soundscape” at the same time. Please allow selecting multiple layers at the same time.