For not wanting to contribute to the holiday?

Just say no, you can’t afford it. Offer to look after their pets while away or something if they have any, to soften the blow.

YANBU.

A few years ago, SIL tried to get DH and their other DSis to buy PIL a new car for their milestone anniversary 🙄. Thankfully it was discussed on the family WhatsApp first (PIL are not in it). DH was on unpaid sick leave at the time, so we very quickly declined saying “how kind of you, unfortunately we are not in a position to contribute.” Needless to say she was less keen when she realise we would not be part-funding HER grand gesture!

They shouldn't have agreed it before they'd even asked you. Just think of they had asked you beforehand, would you have been okay with it?

If so, i'd probably just say yes that's fine this time but please don't agree before asking me first.

If in anyway I did not want to do this I wouldn't be contributing.

They really should have got your agreement first.

I’d say to your parents:

‘Sorry, can’t contribute to the cost of the holiday and had you discussed this prior to telling DB I’d have saved you the embarrassment of now having to explain this to him. However I am happy to put 100 €,£,$’s in a card so DB and GF can enjoy a meal or drinks on me whilst they are away.’

Your child’s milestone birthday is your responsibility to organise just like your siblings milestone birthday is his parents responsibility not yours.

Absolutely ask for contributions to your own holiday. Actually dont, just say no.

This is bonkers. Lovely idea of your parents, but they should be paying the whole lot if it’s something they want to give!

No - I would not be contributing.

For a 21st birthday I would probably pay out more than a normal birthday but would be buying something that would last - a piece of jewellery, etc.

And at 21 who says he will still be with the girlfriend in December. She has plenty of time to save for herself!

I would probably say that I am more than happy to contribute to the holiday funds rather than buying a gift and then specify the amount say £50 that you would usually spend on their gift.

expecting more than that is really cheeky. I remember when we were all told we had to stump up about £100 per couple for my brother in laws (DH’s sisters husband) 40th birthday gift. That was a lot for us at the time (we are much younger and were just starting out as a family with very small kids). But when my 40th rolled around last year I don’t think either of them even remembered to wish me happy birthday let alone buy me anything. Some people expect a lot but don’t give the same thought in return.

This!

There is no chance I would give a gift that large for a birthday. I would tell them I will contribute my normal budgeted amount.

I’d not do it just because sets an annoying precedent that they can unilaterally make such a decision without consulting me. ‘sorry no. I’m not paying for an expensive holiday for my brother, I can’t afford to and never agreed to do so.’

Nah. That’s a parents’ gesture. Absolutely not a sibling and certainly not okay to force you into it with guilt and by embarrassing you.

@TwinklyRoseTurtle Buy him a new suitcase.

Bloody cheek your relative by the way not you.

They had no right to offer up your money and I'd be telling them so(I'm 50 now and stand up for myself I wouldn't have done so in the past)and asking them if they'd be happy if you did the same to them.

you know all this is ridiculous....you are not caught off guard, out of guard or within it. Stop this, now.

If it is normal in your family to split paying for a 21st birthday trip then pay. If not, then don't.
Maybe have a wtf were you thinking chat with your flaky sister for suggesting it. Can't understand why your mum wants to pay the gf's share.

mum, dad, I can’t pay for that holiday. If I can afford it I’ll be taking x away for their 10th birthday. You’d be very welcome to contribute, you could think if it as a very late 21st present for me now that you do huge gestures for these birthdays, you must feel a bit bad that I missed out on all this generosity.

That’s insane. What did they get for your 21st?

I knew it'd be a little brother. It always is!!

Here's £60, you can add the zeros yourselves.

This was my thought @TwinklyRoseTurtle - if the sibling is getting a holiday, perhaps the same can go for the GC?

So someone has proposed buying a young couple a 2.4K holiday as a 21st birthday present for one of them? No, sorry, that's ridiculously excessive unless you're the Branson family. And well out of order with the emotional blackmail.

I think you'd be reasonable to say that financing a present for your own child's approaching big birthday is your priority, so perhaps you can agree that you will do that for YOUR child and in turn your parents can do the equivalent for theirs?

Did you and other sibling get presents remotely in this ballpark for your 21st? I'm guessing not

No way!!!!!

Well after your updates…

”No sorry, my own child isn’t getting a holiday this year so I can’t contribute to siblings when he can pay for it himself “

This is bizarre, why on earth would they suggest such a thing