[verditelabs]

I think you're right about the implicit group/family aspect in many cases. If I'm taking to one friend and say "how are y'all doing" then that friend's family or ingroup is certainly implied in the question.

The singular polite "y'all" I'm referring to is generally used when the other party is not known. F.ex. I regularly, though certainly not always, hear clerks, waiters, or other service industry workers using "y'all" singularly when asking "what can I get y'all to eat" or "y'all need anything else" when speaking to exactly one person, and I use it that way myself.

[pruetj]

Ah, got it. I know what you are referring to now. Yea, it is seen in hospitality more often.