[norwaypinesavage]

"I know enough not to use ‘y’all’ in the singular."

I knew y'all ain't from Texas. "Y'all" IS singular. "Y'alls is plural.

[ROCKLOBSTER]

Yeah, that too.

[Fantasywriter]

So you look at one person and say, in effect, ‘You all’?

Does this individual have multiple personalities?

If the term has a regionalized usage in TX, that’s your affair. Just don’t ask the Deep South to follow suit.