To be annoyed at SIL-to-be?

I think it depends on the hen do itself. If it's just a full blown night out, drink yourselves stupid sort of event, probably just the bride's core friends. If it's a bit less of that, then yes, I'd expect a wider group. In my circle of friends from South Africa, it's pretty common to do something during the day that would be a bit more open and then either on that night or another night, more of a knees up sort of event without the mums/sisters in law etc. sometimes the sisters in law might be invited out of politeness but would equally politely decline, or just come for a drink before "other plans".

The never travelling to you or making the effort is more of an issue. But also, not entirely weird. There's often one family member (and I'm talking about your brother here more) who either always invites to theirs or only ever goes to someone else's.

You are YABU

but without knowing the dynamic in your family, it's impossible to comment further.

Maybe you are in completely different stage of your life, you have young children, maybe they didn't want to settle and do boring family things too soon. Maybe your brother has described you as the favorite child, maybe they are just busy.

I would just chill a bit, be pleasant and see how it goes.

Did you see more of your brother before he met her, or do you actually expect more suddenly?

The groom's sisters/mothers weren't at any of the hen parties I've ever been on.

Everyone does this stuff differently. Plenty of women don't have their own mum or sister at their hen do, let alone their in-laws. Ultimately, you only see your brother twice a year so you don't really know his fiancee very well at all and there's no reason you should be invited to the hen do.

I also think that it's perfectly reasonable that your kids wouldn't be bridesmaids/pageboys. It's completely normal for a bride to have adult bridesmaids/attendants only. I actually can't remember the last time I went to a wedding where there were flower girls or page boys unless the bride's own siblings were still kids.

Well that’s nice and shows that she does care. She obviously just wants a nice day out with friends, presumably who go way back. Stop picking on her, it makes you sound really self-involved. And I’m sure YOU think your kids would be cute in the wedding party. She might not do.

Maybe she doesn't care about you. She's marrying your brother, not you!

Would the grooms family usually be part of the bridal party, surely that's for the brides family/ friends.

I thought a hen do was for the bride and her close friends? If you only meet up with your brother a couple of times a year I'm assuming his fiancee hardly knows you.

I wouldn't expect to be invited (or wish to go) on a hen do where I barely knew the bride and didn't know anyone else at all.

Yeah the hen and stag are for that persons friends and maybe family. Not future I laws so I wouldn’t find that weird. It’s more the norm not to invite than it is.

Again your children being part of the wedding why is the Sil blamed? It’s your brothers wedding too.. his nephews/nieces.

Bur as you’ve concluded the relationship is clearly more invested from one side than the other.

My sil wanted a close relationship and all the cousins to be little best buddies. Her own brother cnba and honestly I’m just not that into her and her children to give them any headspace apart from when actually mentioned or infront of me.

I think it’s a shame that she didn’t invite you, and it’s a mistake on her part. BUT- I would try to look past this and gently get to know her over time. I would really try not to hold it against her and keep an open mind generally. When I think back to when I was getting married, I made a lot of mistakes and was a bit oblivious. I’m grateful that many of the lovely people in my life looked past that and I’ve developed a really strong relationship with my husband’s family as a result.

I wouldn't expect an invite from someone I barely knew.

Depends on then hen do, depends on the relationship. It's not a firm rule, and no, it's not RUDE.

You really need to chill now. She doesn't have to include your family just because she's getting married. See the wedding as a possible way to get closer, maybe you will be compatible, maybe you won't. You might become friendly, you might just stay distant in-laws.

You are not exactly close to your brother. The only people I know who invited their future MIL to their hen had a special afternoon for older "guests", no MIL on the actual hen 😂

Bridal party eh the clue is in the name. And if you are not friends no I wouldn't expect an invite to a hen. Surely you should be asking your brother if he has any plans for involvement in his party?

I’m 30 and in London. In my experience (have attended 4 hen dos in the past 18 months) it’s really normal to invite your husband to be’s sisters to the hen. But I think all the ones I’ve seen invited are close-ish to the bride or have at the very least enjoyed spending some time together pre hen do.

My brother is going on my BIL to be’s stag. They aren’t the best of friends but have spent a lot of time together at family events/holidays.

I didn't invite my prospective SIL to my hen do. They were my closest friends and female relations, and she was neither at that stage.

You said in your OP that you see you brother a couple of times a year, so you probably dont see her very often either?
Do you and your kids know her well?

My SiL (husband's brother's wife - so the widest definition of SiL I suppose) had her hen do 10 minutes up the road from where we live. They live two hours away, so it's not like it was local for her. She didn't invite me for any of it. I have to admit it bothered me at the time because in her shoes I would have asked me for a drink or even a coffee at some point in the weekend. (She literally had to drive past the turning to our village to get to the venue and could even have stopped off for a cuppa on the way there or back).

That said, we weren't close then and haven't got any closer in the decade or so since, so I guess it was a sign of how things were to be. It also made things clear early on, so I've never felt obliged to extend invites where I might otherwise have done (and she's probably glad she's not obliged to attend everything we do).

No bad feeling (now) - just a distance that's never been closed down between us, and I'm fine with that.