This is basically how we handle our daughter. She’s invited to come to the dinner table, but not required–because we want to eat our evening meal like civilized adults. She can have preschooler food in the TV room later.
Call it cop-out parenting, but it’s a battle I simply will not fight. I put my energy into sleep-training instead.
Sometimes holidays are easier with a game system in the TV room as well as a good sized coffee table. Each parent does their own child’s plate, the plate goes with the child into the TV room (may I suggest the semi-indestructible Correlle?)
with forks and spoons only, 1 Playstation controller per child, and have games available that all the kids like and/or can play.
Adults have an Adult dinner (food that’s miles more complex than chicken-nugget chunks) with multiple courses and a good wine. The children may come to the table for dessert (or not, your house rules apply).
Suggestion: Clean up and food packing happens before coffee / dessert are served… and dessert should be pushed off until the very end of the night, with guests expected to be coats on & gone in less than an hour after the slice of cake hits their plate.
This is because the sugar will hit the kids like Nitrous Oxide hits a race car.
(Think of it as “magical holiday energy” to help little legs make it all the way to their car… and all the way home… before falling blissfully asleep. 
)
Pros: A (mostly) adult meal with good conversation, fine food, and good wine. Also, enough leftovers where you won’t have to cook for the next week.
Cons: Glasses & plates in your TV room, possible spills. Some kids will still sing out “MAAA-aaaa-AAAA…!” to try to get their problems resolved (your house rules not withstanding).
You’ll be doing your own clean up and your own dishes… but we’re all adults here… and we ALL do that every night anyway, right?
Technically speaking, it’s not a great chance, but theoretically you might be able to qualify for the Law of Return if you’re being persecuted for eating Chinese and going to the movies on Christmas, which would therefore sort of make you close enough to being Jewish that it’s no longer Appropriation™…
Or, you could just say that Americanized Chinese food is actually Appropriated™ 1850s Californian Gold Country cuisine, so you’re Appropriating™ it back in the name of your grizzled prospector ancestors. Dadgummit.
Sadly, my brother still has meltdowns at holiday family dinners. He’s 26.
This year, he had one over - and I kid you not - the History channel show Ancient Aliens. He actually believes that garbage, and when I suggested to him that he watch a documentary that was made to debunk basically every single claim in the entire series, it did not go well.
So I’m not some heartless Scrooge for thinking some one should have just wrapped the (actually pretty cool) kid in a fluffy blanket with bunnies, and tossed it on a couch with a sippy-cup and a good book? That’s a relief.
And I’ve decided that as long as we don’t go to a movie afterwards, Chinese food is fine. Unless the kids really annoy me, then it’s Indian.
Yeah, as long as the blankie has bunnies you’re cool. Skip the bunnies & we’re callin’ CPS on ya. 
Kids videos changed to accommodate toddlers who have just bitten into “The Heat of 10,000 Suns Vindaloo”:
“Gordon snickered as the mushroom cloud sprouted from a-top Sir Topham Hat’s head. Belle and Flynn squirted water on him madly while Thomas stared in stunned disbelief. Evidently today, Thomas wasn’t very useful at all…”
[Steve] "Whats that Blue…? You want something…? " [/Steve]
<Arf!> <Arf!>
[Steve] “Something in… a glass…?”[/Steve]
<Arf!> <Arf!>
[Steve] “Something… white…?” [/Steve]
<Arf!> … {Breaking Character} “Dammit Steve! Get Me Some Fucking Milk!” {/Breaking Character}
[Barney]“Now Baby Bop! Why did you stab B.J. …? Don’t you know that’s not nice?” [/Barney]
[BabyBop] “oh, Barney! I know… I’m sorry. But the Bastard dosed me with Vindaloo and then he Took My Milk!” [/BabyBop]
“Curious George ate the Vindaloo. And then he tore off the Man’s Yellow Hat.
Witnesses would later say he also tore off Both of his ears and 95% of the surface area of his face…”
Bob The Builder folded his arms. “I’m sorry, JJ, but I don’t have any milk. Maybe Mr Sabatini has some in his Pizza Shop.”
Abuelita had a kiddy set of two minichairs and a minitable. Most of the time, that ensemble lived in the Children’s Room, a tiny bedroom next to the kitchen where we could play to our heart’s content so long as we didn’t hit each other (we were allowed to kill each other, but not to hit each other). We’d also normally eat sit-down meals there when visiting.
If the children present were being proposed as perhaps grownup enough to maybe join the grown-up table next time, that little ensemble would be moved to the dining room and we were allowed to eat there. If we behaved properly, we’d be promoted to the adult table. If any of us didn’t, we had to move everything back to the Children’s Room.
On one hand it’s kind of ridiculously elaborate, and on the other it actually worked beautifully except for A Certain Cousin, but let me put it this way: his firstname is still used as an insult locally, 40 years later. And not just by my family.
Yesterday I got my mother to try Greek food for the first time. She deemed it acceptable. I was having serious problems keeping a straight face watching the way she examined everything before eating it. For Brillat-Savarin’s sake, woman, a slice of tomato is a slice of tomato! It’s a tomato, it doesn’t even talk funny; it doesn’t talk at all!
Well, that’s how it should be done, obviously. You have to teach the kids a modicum of manners and make them aspire to the grown-ups’ table. Unfortunately, I did not have that option.
Okay, I’m going to confess - I caused the melt-down.
I told the child to wait until everyone was seated before eating.
We did get past that, but then I said something else - I really can’t remember, but it was not a threat of physical violence, I swear - and everything went to hell.
So, Nava, when are we going to hear the whole story about your cousin?