What cases can "y'all" work in?
A prior question asks about the 'proper' usage of "y'all", but it and its answers only address nominative case (all examples are nominative).
I think that there are some cases where "y'all" doesn't work as is.
nominative: "Y'all come back now, ya hear?"
accusative: "I'll ring y'all up tomorrow after the fish fry."
possessive: "Bring y'all's swimsuits. The pool will be open." (or "y'allses". yes, I find this is questionable usage)
vocative: "Hey y'all! Where's the keg?"
but instrumental/dative/indirect object?: nothing sounds right.
? I'll bring the BBQ over to y'all.
? This party is all for y'all.
These don't sound right to me. The alternatives that sound right to me would be:
I'll bring the BBQ over to you all.
This party is all for you all.
Can anyone confirm my usage? Has there been a study/paper on this?
I ask because most pronouns in English have forms for different cases, so it is not given that "y'all", though a synonym for "you" which only has a different form in possessive case, would or would not have a different form.