The craft here is admirable. You're working with sound in a traditional way that is appropriate to this form.
And I suppose my chief thought is that I wonder if the form is holding this back. Right now, I think the pace is a bit sluggish, and I wonder if this could be rewritten in couplets. A major overhaul, to be sure. And this could be complete heresy to this project, but I wonder if this could improve the pacing:
The annual dinner was nearly over;
but one at the table was still sober:
Not Arthur the uncle who eighteen months ago
Was O’Reilly there ? We’ll never know.
Not cousin Millicent, said to woo
the butcher, the baker as well as the crew.
Not older brother whose wife agreed
she'd married a drunken pay-no-heed.
Not Aunty Molly reduced to sobs
hearing she was really Uncle's Rob's.
The cupboard is open with skeletons out,
each year they escape. The louder they shout.
I obviously didn't have suggestions for every line, but you see the point that I hope that I'm making. I know this edit is incredibly insensitive to the care that when into your draft. Please don't hate me.
At any rate, there's much joy and enthusiasm in this piece that I fear is being choked off by the form.
Best wishes moving forward with this. I'm really interested in seeing where you take this.