[pessimizer]

> it’s assumed I’m speaking of the family unit that person belongs to rather than the individual.

I think this is the formal singular "y'all" that people keep referring to. It can sometimes be short for "you and your family," which is why you would see it in greetings and goodbyes e.g. "How are y'all doing today" or "I hope to see y'all again soon."

For signs of formality, it has the indirection of not addressing the person directly (like "your grace" "your honor" or "your mercy"), and is usually used as an stylized expression of concern. To my ear, "How was y'all's holidays?" sounds really professional, like how your lawyer would start a meeting.