Should petrol money and accommodation be charged?

Jfc. This along with:

There will not be a 'food shop' - each person is taking a big bag of food from home. Takeaways and alcohol are not part of the plan as no one drinks and two of the three are on a diet

How can you call this a 'holiday'

It sounds miserable AF.

Person C should definitely and non-negotiably pay for their petrol and food share. As for accommodation, C should offer to pay and it's up to the others to accept or not.
Terrible idea, BTW, to bring the additional person. If I were person B I'd probably not go at all.

Always better to err on the side of being too generous than mean or mean-spirited, imho.

It would make life easier all round and reduce the risk of any lingering resentment if C paid a third.

Where did it say C lives alone? The OP said Person C lives with person A.

The full story is in the original post.

No, it’s not, OP-you keep adding bits and not answering questions properly…. you’ve said it’s a caravan for 4, but what bedrooms are there? One double and a twin?

Who is driving?
Is C the child or partner of A?

Has C offered any money? Is A expecting to pay for C?

Has C not already offered? If not that’s very cheeky of them to say they can’t be alone knowing full well A is off on holiday as they were clearly angling for an invite. If A wants to cover C costs then they can but B shouldn’t be expected to if they don’t want to so C could just pay B their share. If the caravan sleeps 4 and has 1 double 2 single (is that correct?) why will the double not be made up, surely that’s only 2 beds with bedding on then? Also if your neither A B or C why are you involved?

So person C "lives alone" but doesn't want to be in a house on their own at night when A and B are on holiday because "usually A is there"?

1. 3 people instead of 2 in a 4 person caravan WILL make a difference. There will be less storage, less space in the fridge, less private space.
2. A should ask C to contribute towards the costs
3. B should not have to pay towards the bedding if they're bringing their own
4. C should offer to pay one third of petrol and caravan (and half the bedding)

If the holiday had been planned for 3 people how would costs have been split?

For a harmonious situation all round it would be better if everyone paid equally their way.

OP you said in the original post that person C lives alone and further comments state now that person C lives with person A. Whichever way it sounds like B has been goaded into agreeing to C tagging along by both A and C. Considering C is all like they cannot be alone for a week it seems to me like they've used their situation to work in their favour to get to tag along on this holiday. Tell person C if they're wanting to tag along they can pay something toward the holiday as person B absolutely shouldn't have to pay half when an unplanned 3rd person is tagging along whilst the 3rd person pays nothing. I can imagine that person C will probably have an impact on some of the original holiday plans

C is a CF who is definitely being manipulative, essentially gatecrashing A & B’s weekend away and then for free

If A wants C to come then total costs should be split into 3 with A&C paying two thirds (how this is split between them is up to them) and B pays one third

Agree with pp that I wouldn’t be surprised if this was A & C’s plan from the start but did it the way they did so B subsidised the cost

That’s what I thought but having read the OP’s posts I think OP is A, C’s mum.

B being A’s good friend (up until now, at least).

Yes person C should pay a third no matter who they are as they are basically having the same as person A and B.

Person C should pay a third unless there is a reason that would be difficult for them, for example if they have recently separated from a partner and gone from shared bills to paying it all or if they have lost a job etc. But even in situations like that person A and B need to both be in agreement and that agreement should have been reached between them before person C was invited.
Being a close family member to one person makes no difference in my opinion, if that person wants to cover 2 thirds because its their family its their choice but the other person shouldn't be obliged to do the same.

Person C should cover food costs would be my suggestion.

I once paid for a holiday and was going to take one of my dogs and have a lively time exploring. Instead I invited a mate. We went in separate cars at her insistence. She said she'd pay for groceries and bought sod all - spent £20. The next shop she said it was My turn and she loaded the trolley with chocolate and crisps and stuff for herself. I'd arranged to catch up with 2 friends. She said she was too ill to go to visit the first one - her turn to drive c40Miles - but came to the secobdbone and was chuffed my friend copped for the whole bill.

Never again ever will I invite someone who is a little down to a holiday, lesson well and truly learnt....

I was in this situation where a vulnerable person was involved in a situation .
Being kind hearted, I thought of a solution after mulling it over in my mind. There was, for me , no cut and dried approach - rather A Loving Approach so I just said to her " Pay me what YOU think is fair." And she was very fair and generous.

If the caravan is for four people and one bed is a double, how can three beds be made up without the double being one of them?

If a 3rd person is added then they need to pay a 3rd of the costs.

I'm 99% sure OP is person C.

Yes they should pay- they’re benefiting from the holidays and surely it changes few things for an and B instead of being only them. C being a relative doesn’t matter at all.

You do realise the use of "bear" rather than "bare" was correct in the original quote? So no it was not SPAG related.

You know how mumsnet works. It always descends into childish bickering over some made up scenario, sometimes totally unrelated to the OP. Enjoy.

If the accommodation is already paid then I wouldn’t ask for anything but petrol and bedding yes I would. Just casually say ok so it’s now £…per person.

I think if that was me in that situation i'd write off the caravan cost as you've already paid that and i'd split the petrol 3 ways.

Tricky only in the sense of close to one of the people. I would suggest Person A lightly suggest to Person B “I wonder if we should ask Person C to contribute towards the petrol and accommodation so it is shared”. If they look aghast maybe they pay all the petrol (if works out similar), or maybe just suggest they pay for the food shop again as long as inline with the share. I probably would have asked when the first comment was mooted.

I think it wise to raise the question, or if Person B is a very good friend, see how the holiday goes (ie Person C is ok), and just forget it.

C doesn’t pay accom, you don’t get invited or told you’re coming on holiday because you need support without also being clearly told cost. Suck it up

You can't know this.

I don't see why B should have her holiday upended and still pay for a holiday for two. Why should she suck it up?