Nice about your great-grandparents! I would imagine it might go something like that today. Such and such is a "family friend," "roomie," or whatever they refer to them as. I would imagine certain people know the truth. I know poly exists. Do they call it that? Probably not. Do they tell the world and show it off? It depends on the individual or their level of comfort. Much like polys today.
Most of my in-laws are very reserved, and to them, what you do behind closed doors needs to stay there. If they do not care to be around something, they express it in a tactful manner. They had no qualms about expressing their need to not see Si or be around her at all. For them, it was unacceptable and left a bad taste in their mouths. They had strong opinions on it, and from birth, they are taught to speak their minds to clear their hearts. On the islands and in their respective homes, the desire for her not to be around was respected.
If I had elected to be more reserved and subtle about my polyamorist choices, it would not have caused such a brouhaha. Of course, this family has a member who was in the postop period from surgery when she shot at her husband, from the bed, because she suspected infidelity. She missed intentionally, but yes, THIS is what I married in to! (And yes, the couple is still married. They celebrated 39 or so years earlier this year.) That is that crazy love.
Ry - Me. Panromantic demisexual with a history of polyamorist tendencies. Married to...
Mr. Grey - The once distant stranger that I complement beautifully. DH of 12 years and father of our (3) children.