Do the Barbarian "Call of the Ancients" rune "Together as One" and "Unity" ring stack?

Unity: "All damage taken is split between wearers of this item"

Call of the Ancients - Together as One: "50% of all damage dealt to you is instead redirected to the ancients"

I'm looking to increase my toughness to hit high-end greater rifts. Damage output is definitely there, but survivability is still a major issue. I wonder if those two effects would stack for a 75% damage decrease (50% and then another 50% applied to the remainder, I would assume.)

After attempting a GR55 last night it seemed as if they canceled each other out somehow. (Either that, or I'm far more squishy than I thought at 15.3 million toughness and 663k recovery)

Does anyone know if this works?

Edit I'm using the following build: Grift 75+ Hota Barb (Group Build)