Rotate a cubemap in a material by another actor?

I’m looking to rotate a universe (stars, moon, etc) around a static reflective object. To get a consistent reflection, I put a cubemap in the material and plugged it into an emissive leveraging the reflection vector. However I’d like to tether/inform it by my actor that rotates the world that’s acting as the pivot for the universe. I tried creating a dynamic material instance that talks to a parameter in the material, but I can’t seem to drag my rotating actor into the event graph. I can get the cubemap to show up for the object in question or for a rotation tied to the player, but not for another actor. Any help is incredibly appreciated. I’ve done a lot of research and can’t find the right combination of things I need and I’m running out of time.

Thanks in advance! Attached are my material, construction, and event graphs.

Can anyone give me a quick answer?