I donít know if this well help, but George Jardine showed me a tip that I think works really well in general; leave Blacks alone, tweak the Shadows slider instead. Its definitely not the same, but I find it provides the rendering Iím trying to produce instead of using the Black slider.
While a lot more work, a technique that works really well for handling these shadows is to build a grayscale mask for Photoshop that targets only shadows. Load that and use Hue/Sat. You can actually build a really good mask in Lightroom that targets just shadows, convert to B&W and render. That iteration will have three identical RGB channels you can use to load into the original RGB file (Load Selection). In the past, the trick was to make a dupe of the master (duplicate), convert to CMYK and use the black channel as the mask to load for shadows, usually after pulling curves or Levels. The idea is to produce a grayscale single channel file (or one of the composite channels) that only has white on the image for the shadows, black (protect) for everything else.
Simpler but less effective is Color range, Target shadows. Desaturate what it selects (but its a crude selection).