‘Child-free’ wedding

I think your problem is that your fiance made a unilateral decision about this. That is what would nark me.

However, it could have been agreed on in the same way that I agreed with my exH because I (fiance) hasn't thought the whole thing through and was hoping that he would get away with it instead of trying to reason with the bride (in my case my exH who was a bully).
My point is that he could just have gone along with this rather than actually it being what he wanted.

Well OP, been there done that ... with my ex-H; he wanted child-free, me not so keen; ended up with my DSiL upset as my nephew and niece were totally excluded too (he refused for them to be any part in the wedding at all). This didn't pan out so well for us and was always a point of tension.
How far away is the wedding and what sort is it? Is there any way you could include all the children but avoid having to pay for an expensive sit-down meal. You would however have to pay someone to look after them.

They genuinely get a lot out of it, they're great family experiences. There's rarely bad behaviour in my experience.

Stand your ground. DF can't decide to go back on what you agreed on and as you said, it also won't be fair to those who have gone to the effort to sort childcare.

Other people enjoying weddings with children there or some children enjoying weddings are irrelevant. It's your wedding and it is what was agreed on.

We attended a friends wedding years ago, we had kids at the time.
It was kids free, no issue as it was local.
Some cousin of the bride turned up with a 12 year old girl, husband and she were part of our table.
She never shut up.
Dominated the conversation despite being asked to tone it down by two people at the table, not by her parents I might add.

We finished the main course and we had enough.
We left the table and had our desert in the garden.
We were quickly followed by 8 others.
It was appallingly rude of the parents to not ask her to give it a rest.
They smiled indulgently, most bizarre.

I heard afterwards that she had been specifically told no to bringing her child by the bride.

She just ignored it and turned up.
The bride was very pissed off and told her mother and aunt just how upset she was after the wedding.
There was a big family fallout.

It certainly ruined the meal for us and others as the empty table was testament to.

Some 10-12 years could happily join a table and know how to behave, but not all.

My sibling just got married and it was genuinely an incredible life experience for my 10 and 13 year olds. Including my son who usually prefers the PlayStation to chatting to adults!@

I can't imagine leaving such close family out if a major celebration like this

100% guarantee that OP will be back here in 2-3 years time complaining that the in laws have no interest in her precious child.

I hate taking my kids to weddings! way easier without them! i can enjoy myself and have drinks and stay at the hotel and not have to get up with them in the morning.

We took my 3 year old to a wedding last year and i spent the whole day following her around - my husband and I had to take turns taking her outside for a run around during the meal - I barely got to catch up with anyone.

I left her behind with husband at my own sisters wedding as it was actually just easier that way

Id not invite him if thats what you want! brothers wife can miss out - what does it matter ! A wedding is just dinner and drinks and dancing - she wont miss much.

I think leaving out family children is a shame

I don’t think you need to feel bad about bridesmaids tbh. Most people (unless they’re completely unreasonable) understand that the nephew of the groom is not the same as a friend’s child when it comes to wedding invitations. I’ve been to childfree weddings where the bride’s nephew was there - it didn’t cross my mind to think “hang on, it’s not fair that the bride’s close relative is here and not my child!”

Yes it's his wedding too but if they made a decision together I think it's disrespectful to override it without consulting his fiancée.

I just don't even understand child free weddings as a concept. It's such an arbitrary way to exclude a whole bunch of people, especially if you exclude older children too, like 10yos who play quietly on their Nintendo.

Imagine if you said "no over 65s at my wedding, they spoil the vibe".

Unless you were the bride's sister it's not remotely comparable.

The groom's nephew (especially as it sounds like he's the only nephew/niece) attending a generally childfree wedding isn't unusual or something for people to get mardy about.

Not really. Why would we attend a wedding centred around family when they didn't want family there? Either immediate family attends, or they don't. Her choice. You'd only be pissed off if your priority is to have an Instagram wedding rather than for deeper reasons.

Mine behaved well at weddings. It's important to get them used to mixing socially. Most children are perfectly capable of sitting through a ceremony and speeches. They're usually happy with the attention!
I've been to many weddings where children were always well behaved, but in my culture we don't tend to exclude them from events.

That all sounds like emotional blackmail by you and your parents. I'd be pissed off if I were your sister.

Hold the line. Childfree means all children, not just everyone else’s.

I've only ever noticed children (including mine) being a PITA at weddings. It's really boring for them sitting through speeches and eating at long meals.

Thankfully, most we're invited to are child-free.

Then it'll be up to his wife too look after her DS...
If she plans not to then she can do as she's threatening and stay home with him.

I do understand where you're coming from though.
Although equally guests should recognise that although it's stated as child free families DC will still be included.

Eugh, if I was maid of honour for my sister and she said her niece or nephew couldn't come I'd be so pissed off. In fact, that nearly did happen, and it nearly blew the family apart as our parents said they wouldn't come either as what was the point of getting married and joining families together if you didn't want the family there to celebrate.

I think it's perfectly acceptable even at a child free wedding to invite close family children. He is your nephew after all and so I think it would be nice to invite him. It seems unnecessarily harsh to exclude him regardless of your feelings for him. Your bridesmaids will understand you making an exception for close family children.

It's his wedding too.

He's going to look like he's under the thumb if he said - I need to consult first - he's made up his mind his brother and SIL mean more to him than a child free wedding.

Even if he did consult what was Op going to say stick to her guns and cause a fall out between her and DF or him and his family.