Child-free Wedding

I’d just let her bring him, she’s your MOH and you’ve already told her he is exempt from your child free rule

It's understandable that she is still expecting her child to attend, since she knew you were already making an exception for him at the original venue. And that expectation will have been confirmed by the fact that you didn't say anything to her when she has mentioned him attending since you changed the venue.

I think you need to let her bring him - to withdraw the invitation now would be quite upsetting for her, and might also cause problems as she will have to find childcare for him. Presumably she has a partner or other family member attending the wedding who will be responsible for him? I really don't think you need to worry - it's true that kids that age can be quite lively, but most parents are used to keeping an eye on their kids, providing them with things to keep them occupied and taking them out if they get noisy.

You perhaps should have made things a little clearer at the point things changed. We are having a “semi” child free wedding (only family kids and those of the bridal party!) could you maybe stretch to that instead? Have you any family children that can come along to even it out? X

When you did the invites with her that was the time to have the conversation, hindsight is a wonderful thing and you are were you are. Maybe approach her and say that as she knows things have changed and you wanted to clarify her understanding around her son and whilst you have not explicitly said it, the child free extends to her and you are sorry if you had not made this clear when you changed your location etc. Play it that he is welcome as you appreciate your original agreement and you don't want it to be awkward but highlight he will be the only child there so may be bored and did she want to maybe consider him not coming and have a night off? He will be old enough to be left with a family member, is not like she is breastfeeding, and if it were me I would jump at the chance of a child free day/eve! Im honesty it is a bit late so you need to respect she may decline and still bring him, or you need to put your foot down if it is stressing you that much but be prepared that she may say she isn't coming at al. If he does come set some rules such as he sits with Dad and they have an exit route and dad will discreetly leave the ceremony if he makes a fuss, which is not an unreasonable request

I think it is a bit late to withdraw the invite for him I’m afraid. But you need to make her aware that he will be the only child and could be very bored.
We have no children at our wedding except my 2 girls (aged 12 and 14) and my sisters 3 kids who will be 3, 8 and 10. They are all part of the bridal party. I explained by group message to my uni friends that no kids are invited. A few of my mates replied to say great and that they couldn’t wait for a night off. One friend however totally missed the message and when it came to booking hotels she asked about breakfast as said her kids get up at 6.30 and will be starving. I realised she thought her three kids were in invited! I jumped on that straight away and said - er you know we are not having any kids at the wedding except mine and my sisters who are all in the bridal party?? She replied saying she missed that and that it would be a challenge🙈 (she lives in Malaysia and is coming over in the summer for 2 months for mine and another family members weddings)
I had to nip it in the bud straight away and she has been a bit moany about it to other friends as they have told me but there is no way I was having her three kids ( hers are a lot younger than mine too) and no one else’s! It had to be said. She is now coming on her own and leaving kids with husband in this country which I would personally love as it’s a day and night off! 🤣🤣Ask her how she feels if her kid is the only one and maybe extend an invite to a few other family kids if that will help. Otherwise he may be bored and play up.