To think we shouldn't be treated like mealtime maids

Eat at a different time without them.
it’s your holiday.
Unless someone else paid for it you can do what you want.

Well, you say "In my family, all the adults who don't spend their lives caring for the child with additional needs (or any children, actually)"

The OP has two children of her own. Not ND (I assume) but anyone would agree two can be a handful. Where is her break? Who from the family is stepping up to help her?

Instead, on her holiday, she is still doing everything for her two children AND for someone else's one. Why is no other adult recognising that and offering support?

Did you discuss receiving the extra support on holiday beforehand?

your needs and wishes should be taken into account. I always preferred to be with the children away from the adults, not only just for meal times, so it wouldn’t bother me.
However, not everyone has family like mine

No one should dump their kids on you especially if the child is difficult.

What a dumb thing to say. This is a holiday for everyone, not just parents of a more difficult child.

This is why I’d only go away with immediate family for any length of time. People are annoying, particularly when you’re related to them!

I wouldn't be happy with this, either, frankly. When OP agreed to come on a group holiday I doubt she was aware at the time that others had assumed she was signing up for free, not to mention unreciprocal, child supervision.

In view of the fact that I hadn't even been asked, I would not be taking this on. On an alternating basis or otherwise.

If the parents had wanted to reach such an agreement then the time for negotiation was before booking. It would now be an unequivocal 'no' from me.

Play stupid games, win stupid prizes.

Just do your own thing. I couldn't abide having mealtimes and places dictated to me.

Say it- your turn to get a bit of time with the kids- warm smile, then stand over them until they move😉

I'm confused by the scenario you set out. It sounds like you and your kids sat at a separate table to your in-laws and DH and that was totally fine until your nephew joined your table and his parents sat at the other one.

Is that what happened?

I’d say to the family that me and DP feel like we’re sitting at the kids table every night and would like to sit with the other adults so let’s start booking tables that work. Either that or the other parents can take it in turns.

Also don’t parent the child. If he runs off call DB to go and sort it.

Why can't you just say 'Can we take turns to sit with DC? You two do one night and we'll do the next?' Job done.

Ignore this ridiculous comment, OP.

You have your own young children to worry about, and it's YOUR holiday too to enjoy your family and take a breather from parenting your own DCs. It is NOT your responsibility to take over the parenting of someone else's child because they can't be arsed and think they're entitled to dump their child on other people. And without discussion at that!

Suggest you take it in turns to sit with the kids.

Ah, got it.

It's ok to be treated as a mealtime maid by your husband, but not ok for others to see that example and copy.

Got it.

She doesn't mind dining with her own children.

My DS used to be like this. Still is as a young adult but has slowed down a bit. DD is good at sitting but can get distracted by obsessions. Both have autism and ADHD. We found DS stays at the table with us if he is first to sit down and if we can get a booth and put him in the corner so he can't get up and walk around. He is more comfortable doing this. He doesn't sit so well on a dining chair in a restaurant.

He's not to bad at home or where he lives in sheltered housing. As long as his back is facing a wall he feels secure and has to be first to sit down. He struggles to sit down at a table with others already seated. He can't deal with lots of faces at once. Also if the restaurant is busy/noisy that's a no go we go somewhere else. A distraction is good. Does he have an iPad tablet or Switch he can play on? I used to take books to read them for mine when they were younger.

He probably gets over excited and over stimulated being on holiday with all the family.

I don’t think you are being at all unreasonable, OP. My SiL does this. She has two kids, one of whom is quite tricky (being assessed for ADHD) and I have one, pretty well behaved, child. The family have a joint holiday home and when we all come together, if I am playing with my child and the others join in, SiL will just waltz off leaving me with 3 kids. Once she just buggered off for an hour’s walk without saying anything, even though everyone but me was out! I’m not a bloody servant.

My view is that there is a huge difference in asking me to help - which I do sometimes and don’t mind - and expecting me to do it/foisting the children on me. I know it’s tiring having 2 kids and even harder when one is tricky, but she and her DH don’t work and the kids are at school most of the time so they have breaks, whereas my DH and I work full time - so frankly need a break more.

I started being alert to it and stopping it before it happened. “Are you going somewhere [SiL]? Maybe you should take your kids as I can’t watch them all.” She soon got the message and doesn’t do it anymore. Interestingly it improved our relationship.

In your situation, I would have a calm chat, well before dinner, before you start to resent them and explode. Say you think it’s a good idea to take turns if the kids want to eat together. But if they don’t want to look after your two, then perhaps better to separate the kids since they have enough time playing together during the day. Something like that. If you don’t nip it in the bud, this will become the norm.

It's interesting that everyone is talking about bil for leaving his kid with op - and nobody but me paying attention to the fact that her own husband was happy to leave both his kids with op and sit at the other table.

Why don't you just say to your inlaws, we've done a few mealtimes supervising the kids so it's your turn tomorrow so we can have a peaceful meal, I think we really should take turns.

You’ve got two kids, you’re getting on parenting them. If BIL and wife need help with their one child they can ask the other adults who aren’t already looking after children.

Is this new behaviour from them?

They seem to have unilaterally decided that this holiday is a lovely chance for them to spend some time together relaxing and having a break from parenting, but forgot to inform anyone else about this respite arrangement!

Are you going to say something, @LoveBlueCheese ?

You have to set boundaries, especially when other people have none.

I would talk to the BIL and SIl outside of meetings. They should take the next meal. Set a boundary for what you need. "it is unfair for you to leave all mealtimes to us. As nice as it is for the the DC to get together, this is disruptive. In future, you need to take over primary care of x over mealtimes. " It is not ok for them to eat meals uninterrupted, esp without a prior agreement from you both.

Thai is not the time for snarky comments.

It's not about neurodiversity. It's the foisting of responsibility for their own child onto others, without even the courtesy of asking them if they'd mind, that would stick in the craw. That's just rude, entitled and extremely inconsiderate. Good on MiL for pulling them up on this.

If struggling parents are in need of help then what they need to do is ask, not assume. It's about basic courtesy.

YANBU, OP, and you are a braver woman than I. The very idea of holidaying with in-laws is too horrible to contemplate.

Speak up and take turns is the most obvious solution. Keep communication channels open.