All my immediate family are going to my niece's wedding except me

I know I can't go as my BIL has 3 siblings who have not been invited and if I go it will cause him huge problems

Exactly this, If you went to the wedding then they would have to invite the BILs siblings too. Otherwise they might all be hurt too. Assuming spouses are being invited that would be any extra 8 people plus potentially kids too.

I'd be sad too but I would understand it. I think you were a little unfair to make your sister feel bad about it. How about doing something special to commemorate the wedding. Maybe a lovely meal out for your side of the family.

You chose that, and you chose to believe that you had an obligation to put other peoples’ wishes and ‘family arrangements’ before your own. As is your prerogative. I don’t for a moment think that this is a general obligation, though.

I think your sister didn’t think it through at all.
She thought it would be lovely (and cheaper) to have her brother as the photographer, never thinking it was in essence excluding you.

As it was supposed to be a small wedding with only very close family, it was a very bad move from your sister. She basically over rode her dd wishes to insert one of her siblings. (Let’s be honest, a professional photographer wouldn’t get a seat at the reception etc… whereas your brother will. Which they both know).

But you’ll be told to keep quiet so to not upset the bride and your brother is just doing a good deed…..
Also because there is no way out. They can’t invite you because that would be crap towards her fiancé family. She can’t tell brother he isn’t the photographer because he is going to be hugely upset etc….

It’s not a popular view, but my view is that weddings are not about what the bride is wants. They are officially public occasions in which a legal contract is signed before witnesses. They are also a rite of passage with social expectations, the breaking of which can cause real hurt if not handled delicately. This means that you have the wedding your circumstances demand. If eloping will devastate your mother, you don’t do it. If having a small wedding means leaving out an aunt but not an uncle, you don’t do it. Unless, of course she doesn’t mind. Not inviting you because your brother in law has siblings is not a good reason. They aren’t your relatives. They aren’t your concern. If they are all very close to your niece, maybe the small wedding isn’t a good idea. It’s one day. She can have a small anniversary or birthday or whatever else.

I didn’t have an expensive wedding and I’m not an extroverted party person, but I had 120 guests because this is what our family arrangements demanded. I grew up in a village where everyone knows everyone and it was necessary. There were probably another 60 people in the church who we didn’t invite to the reception, but who came because it’s a public event that they are entitled to come to. And old ladies love a good wedding. It’s Saturday entertainment.

Have you any other siblings not going?

I think you’re making it all about you. It’s just parents, grandparents and siblings. Your brother is only there as free labour. You know precisely why you weren’t invited, and why the other aunts and uncles of the couple weren’t invited. Poor form of you to complain.

YABU. You've said yourself that it wouldn't be right to invite you and not the grooms aunts/uncles, what did you hope to achieve by complaining? She didn't even invite your brother, her parents did.
If it gets back to her that you are upset by this it will do nothing except spoil the day for them. The only way they could 'fix' it is to invite more people and make the wedding bigger. Which means they would not be having the wedding they want, purely to keep other people happy.

Very hurtful.
What on earth were they thinking.
I wouldn't say anything further.
You told them, they know.

Don’t be so obtuse. He’s still invited, which means all of the OP’s small family except her is going to this small family wedding. Of course it’s hurtful.

One uncle was invited to take photos, it just so happens he's your brother. 3 other aunts/uncles of the bride haven't been invited, and I presume others on the groom's side haven't been invited either. They've not snubbed you on purpose.

he is invited as the photographer. full stop.
what is the issue

Offer to do the catering?

No siblings allowed apart from someone with an unpaid role. I understand why you're upset but think you're unreasonable for making them feel bad. If you end up getting your way you would have forced their hand, either financially or by them upsetting the other siblings.

That’s a real shame and I’m not surprised you’re upset about it. Very thoughtless.

Well you say they are close, you'd think they'd be aware that you're upset to be left out. I don't understand why your niece is devastated, surely she could invite you if she wanted to? There's no rule saying if you invite one aunt you have to invite them all. People invite those they are closest to. They shouldn't be surprised at your reaction when they have made it clear how important you are to them.

I had a really small wedding as in 2 witnesses, one of whom was my sister. My brother was hurt that he wasn't invited as there are 3 of us, but if we invited him then we would have had to invite my BIL as my siblings were there and he wasn't, plus my SIL. If they were invited my FIL would have expected an invite, and on it went. I don't have any regret but keeping a wedding small means someone's feelings are going to get hurt sadly.

I am cheeky but if I was as close to your sister as you are, I would ask to be given a job so I could go.

I don't think it's anything personal, but they've hurt you and potentially the aunts and uncles on the other side of the family (if they find out) because they wanted free photos.

Oh wow. They've been really insensitive about this haven't they? I'm not surprised you're upset. I think your sister and BIL have made things quite difficult for your DN as well as you. I don't think there's any way to fix this really. I think you need to do your best to show your DN you're happy for her and maybe to protect your own feelings just back away from your sister for a bit.

If he's taking photos then he isn't really there as a guest. He will be focusing on getting the photos so not really enjoying the wedding as such.

if it's his job or even if he's a keen but good amateur, then he's doing them a pretty expensive favour. I mean when we got married nearly 30 years ago we paid about £500 and that wasn't the most expensive one we looked at.

I think you've been mean to mention it to your sister, because it sounds very much as though it's one of those things that happened, not a deliberate slight, and you've now put her (and potentially your niece if it gets back to her) in an awkward situation.

One of those times when you should have licked your wounds, gone away and thought about it and realised it wasn't about you.

Your brother is there as free labour, not as a guest.

They want a tiny/cheap wedding, its really unfair to make anyone feel bad about that. Let them have their day their way.

We did similar - had a tiny wedding (only our parents and siblings invited). One of my husbands uncles is a keen amateur photographer, and my MIL asked if he could take some photos of the ceremony. We wouldn't have had any photos otherwise, so were delighted. But he didn't come to the meal and he wasn't part of the wedding. I hope that none of my MIL's other siblings were upset. It certainly wasn't intended as a snub.

Could you offer to do the flowers to be part of the preparation, even if you aren't included in the event itself? Their decision to have a small wedding isn't a reflection on how much your neice loves and values you, so please try not to see it as such.

So who has done the guest list? Your niece or your sister?

That is really thoughtless of them and they should feel a little bad about upsetting you. But I guess there is not much you can really do.

It's fine. It's her wedding, not your social occasion.

'Inviting aunty wotsit because it's the done thing' is exactly what people want to avoid by having a small wedding.