Why do some people spell it "ya'll"? I've never figured that one out :)
Differences between y'all, all y'all, you'ins, we'ins, all we'ins, etc., are apparent to Southerners.
If you move to Dixie from "up Nawth" and bear children south of the Mason-Dixon Line, those children are not considered "Southerners".
After all, if a cat has kittens in an old stove, y'all don't call 'em biscuits, do ya?
So then what happens when one parent is from the Norwegian North, one is from the South, and they have kids in the Southwest?
I think you'd probably end up with kids that say y'all, all y'all and love to eat hotdish with hot sauce (or casserole, as some "up nort" states call it).