That's for the Neanderthals to do, up next after this.
At first I tried masking out the ashes from the glow by adding the glowing surface shaders, but luminance apparently can't be 'caught'. I tried 'luminance to scalar', but that didn't work either (strange?), so I had to mix the original masks.
Anyway, I also made a vdisp 32-bit 'logpile' as basis for the glowing embers; the lattter two renders.