Outer cylinder precedence is set to 1, water set to 2 and is extended into the glass just barely per nik's instructions. This works. The inner bulbs are set to 1 as they are should be displacing the same water and should take precedence, and the fluids inside them are set to 3. Because 2 made them black and have no surface reflections, although technically since they're still inside the water too that should have worked AFAIK just with no highlights. Oh well. But - look closely at the fluid inside the bulbs, you can clearly see the edges scaled in between the glass walls, which shouldn't happen as that's what precedence is all about. I thought perhaps I scaled the fluids too large, past the .2-1mm boundary, but no, I got the camera inside the bulb and scaled the fluid until it -just- disappeared under the inside surface. And, rendering the bulbs without the water and glass column in the scene, the displacement happens as expected. So - why did the glass bulbs did not displace the internal fluids? Does nesting displacements with precedence not work?
Another nasty (annoyance, really) is that colors don't work at the same level. Red is 50, but trying to get each of the other colored fluids to match in color density requires tweaking each one individually. Yellow is 75 and green is 10. Orange is nearly brown at the same gain as red. Blue is the worst, at 1 it's nearly clear, 10, it's slightly blue, but 25 and it comes out purple?? Also, you'll notice the colors inside the glass are blown out completely.
It's much better than my last version, but I started typing up a document for wiki on precedence and the damn thing didn't behave!
edit: forgot an attachment
