By golly … it worked. In particular, it was your 3rd step above that I was neglecting in previous attempts at direct communication. I was struggling and failing to set the default variable value (reference name, i.e. adome) through the Blueprint editor, and it didn’t occur to me that the default was set through the details panel of the corresponding world outliner object. Such a simple step as well …
I cannot thank you enough for taking the time to help me out with this. Much appreciated.