Twin brother expects us to host every time

This is the bit I don't understand. Birthday person pays (strange to me but ok if that's your family dynamic), but surely if there's 2 birthday people, they split the cost? And if not, why not? I can't think of any acceptable response to that.

Maybe it's just as well if OP is able to keep up the front that it's all just lighthearted. Because it will never, ever be any different. Neither OP nor - crucially - her husband is prepared to change anything. They will both still be feeding this dysfunctional family dynamic (and still feeding LazyTwin and LazySIL) for decades into the future.

At their 60th, 70th, 80th and 90th birthday parties (and at soooo many events in between), OP will be catering for both of them. Luckily LazyTwin will inherit the PILs' money (because he's a special boy and needs it), so OP and her husband might not be paying for all of his care home costs. Just some of them. Ho ho ho, there's no fun like being the least favoured child and accepting that position forever!

I agree, nothing is going to change because no one - including the OP and her H want to change anything. Which I think OP knows and maybe has just come on here to vent. And given you can't / won't change the rest of the family's behaviour (including your H's) you need to change yours -which means either putting up wtih it all, or saying something and distancing yourself.

Personally in the past I was expected to host most things as I had the largest house, but I did share the load by getting people to bring food and drink etc.

Honestly OP reading your post and updates the issue is your DH. He wants to celebrate his birthday with the family but won’t set boundaries. I’d be telling him to complain to the right people or not at all.
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Absolutely.

Even if doormat twin husband is a high earner and CF twin brother is a carer, there still shouldn’t be the expectation that the high earner always pays and hosts.

For this to be going on for decades with doormat twin saying nothing, he’s probably not going to change now though!

So let it.

This is just pathetic. Honestly.

This is for your DH to sort out. I would literally do nothing. This includes any organising or preparation for the party.

I'd warn my DH in advance that i've had enough and he's on his own with it.
Any requests for cake or whatever would get referred back to DH. I'd be tempted to not even be there on the day and say to DH you'd like to treat him to a birthday restaurant dinner the following week.

You are helping to enable this dysfunctional setup.

DH wants to celebrate his milestone birthday with his parents and all of his siblings. He does not want to host. But because his twin has said that he cannot host, it is looking like we will be having the meal here by default.

To be fair to DH, he does do most of the cooking when his family come.
The issue in the communication is that it’s between the twins themselves—I’m not involved. Literally the only time I was put in the loop was when his DW was sending her “requests” via email for the last milestone dinner. We literally have not emailed or texted in a decade.

These are OP's own words.

Her DH wants to celebrate with his family. His twin brother has done what OP would like to do around hosting, which he is perfectly entitled to do and many posters have been encouraging OP to do.

As her DH wants it and does most of the cooking anyway, I say it's his party, let him cry if he wants to crack on.

Surely your DH can say to his own twin brother ‘it’s your turn to either host or pay. You’re taking the piss.’

The husband wants to celebrate with his family

There is a similar (ish) dynamic in DH’s family and we host every Christmas and Easter - with the family coming to stay for 3 or 4 days (sometimes a week!) each time. We also host ad hoc during the year during half terms etc.

About 5 years ago I properly lost my shit over it, especially because DH and I are the only ones who work (family is wealthy but DH and I think work is important so we don’t just live off the increasingly dwindling inheritance…) and in my view the rest of them are entitled and lazy.

Anyway, I told DH that I would just no longer accept it. I would no longer have DH and I carry the burden of being responsible for planning, cooking, arranging and paying for what amounted to approx 2 to 3 weeks a year when no one ever offers to reciprocate or help. So I decided that we would “host” in that they could stay at our house but each (adult) person would be responsible for a day each. They are expected to plan, shop and cook. Everyone has to pitch in to help clear and tidy. I usually take charge of the “big” meals (because I prefer my own cooking!) but the cost and execution of the others falls on them. There was some initial grumbling, but I ignored it and they have now accepted it and this is now the norm. They know the spreadsheet is coming a few weeks before each event! Perhaps they don’t like it but they don’t say anything and I wouldn’t care anyway!

I guess what I am trying to say with my somewhat long winded anecdote/vent, is that dynamics can change. But you have to be willing to make it happen and stand your ground. In your situation, I would make the next birthday meal one where you assign each a course/dish OR insist it be a restaurant where every family group pays for themselves. Their choice. You don’t need to frame it as “you’re useless parents/people”, just say you are finding it too much now and it is time for everyone to pitch in. Nothing will change until you make it change. But it can work, I promise!

I think I'd get out ahead of it and text twins partner etc saying do ye want to celebrate together etc and iif they say yes id say can you starters and dessert and we'll do main and host? With people like this you need to be blunt.

Ask DH why he doesn't want to spend his birthday with you doing something special and adult? Because when he thinks about it, he may realise he's resorting to childhood patterns simply through habit and/or fear of upsetting the apple cart and decide to break them.

Although not twins, my DH and I are both responsible siblings. We decided we had had enough, so stopped engaging with it. From my not very random sample of two mollycoddling mothers, I would would imagine your MIL’s instinct to mollycoddle LT will be her overarching emotion in any situation. once you start being very firm and sticking to your guns, id be really surprised if she didn’t expend more energy on solving LTs issues than pressuring your DH.

which isn’t to say that he won’t initially be met with a lot of pressure to fall in to line. But when he doesn’t bow down to that, their main focus will be on finding someone else to solve his life for him. You might be met with a few days of moaning or sulking, but then they’ll move on and pretend it never happened.

In this specific situation I’d probably find out what DH wanted to do, and then act accordingly; communicate to everyone else what is happening and stick to facts. That might look like, DH has suggested going here, the cost per head will be x, or it might be everyone is invited to our house, mil please bring x and LT/sil, I will leave you to arrange the cake. Whatever you do, present it as decision rather than a negotiation, and if they push back, say ‘well, we are organising x, y and Z, so I’ll let you and MiL lease between yourselves. And then leave them to it (/turn your phones off!)

This ☝️ 💣 💥

Play her at her own game

Tell her what cake your husband wants and to find a venue and say in sure mil will bring the sausage rolls

Your DH's family all sound awful in different ways. Mothers like your MIL who don't think that any woman is good enough for their precious sons are pathetic. Your FIL expects you and your DH to treat LT like a vulnerable child who needs needs to be mollycoddled and subsidised and LT's wife sounds as entitled as he is.

Are you able to vent to your DH about their entitled behaviour or would he be upset if he knew that you didn't view them through the same rose-coloured glasses as your DH?

You offer to have the gathering at your house, twin & SIL can arrange the catering as you’ve organised every other year and are feeling ‘stressed with work/unwell/facing redundancy..’ therefore can’t cope with the extra stress at the the moment.

You say that as though it is a bad thing?

Why - what is the problem long term with a grenade called "make LT and his enabling parents grow the hell up" ?

I understand - but you've not responded to the hundreds of posts which say your DH needs to do so.

Well stop having "birthday meals for the family" for a start!