Drama free option?

[RiddleMeThis3]

There are six kids on my H2B's immediate side of the family. We have no kids ourselves and aren't kid people, so we ideally wanted an adult only wedding.

We couldn't figure out how to best get this message across without causing problems, so we said we'd see how our subtle hints panned out (our fault, I know). Sister 1 and 2 said they'd like each of their kids to attend the ceremony and then be picked up to go home. We were delighted! That's a good enough compromise. Sister 3 has said she's having one of her kids picked up but her daughter will be going.

So, this means one child at the whole reception, among a room full of adults who'll be having a few drinks. She'll be bored and it's not in a hotel so she can't head off to the room with a parent for a break. It's nothing against her personally but I just don't want her there. She already talk about the wedding like she's going, so what do I do here?

I would ask your sister to have her daughter picked up too. phrase it as 'it's lovely that kid1 and kid2 are coming to the ceremony, I will be pleased to see them there. However, the evening is adults only, so please can I ask that kid2 is picked up along with kid1?'
I wouldn't be offended if i received a text like that.

This sister can be quite volatile and I'm genuinely worried about the prospect of a huge argument. Would you be ok to get a text like that if your child had to be told "You know the way you thought you were going to that wedding? Well you're not"? I genuinely can't fathom why the kid would care but she's apparently "really excited" and keeps asking if she can be a bridesmaid.

Offer to sort her a babysitter and provide pizza?
I feel your pain. My friend didn't get my subtle hints and her dd turned up in a bright fuschia dress - looked like where's bloody Wally on all our pics!
Spell it out op.

Crikey 🙈 What a colourful memory! Same in this case, the kid has a really brightly coloured dress to wear. I feel like it might be too late to say something because it's not ok to upset the kid? My H2B is like "What's the big deal if she's there?" and I don't really have a good enough reason other than I only want adults 🤷🏻‍♀️

I think the drama free option would be to let her come. Buy a few colouring books and some markers for her (depending on age) and let her sit in a corner and crack on. Your SIL will have to deal with her and you will honestly barely notice she's there! It goes by so fast!

It's a bit late now, you haven't made it clear and the child thinks she's invited and attending.
You'll hurt feelings etc by saying she can't come at this point. I don't really see why it's a problem, 1 kid.
If you didn't want to have children there (even family member's children) you should have been very clear and polite about it from the outset with everyone.