How would you split this cost?

The most crucial thing is for everything to be crystal clear and that people are told what’s happening as soon as possible. I’d also get the money paid in advance if possible .

Accommodation is paid by those using it. (Paid individually but as a pp mention check if the hotel does a deal if using catering/hall).

Hire of the hall/catering should be split among those using it, obviously not DG.
Could do it as a ratio . Obviously all adults pay towards, those with kids pay accordingly, if they have 6 they will significantly more than those with 0 or 1 ( like having a normal meal out, if all 6 kids eat then uou pay their bill!)

Accommodation - split between each family needing it.

Meal -
‘Adult’ = adult = teens = 2 children (under 12)

Split meal equally per ‘adult’ (see above)

It sounds like a bit of a dear do if accommodation for quite large families is involved and the catering is full price for children. I think if we’d had a big milestone do for one of our parents my sister and I would probably have split it, but not accommodation. When we shared a holiday house we worked it out on the basis of half price for kids and each family paid their own share.

Everyone pays their own way, except granny who you split between the adults

The difficulty is that the son has set a precedent by paying previously and now it is expected by some. I would split per head, it’s not fair that people with fewer children pay the same as the family of 6. They should expect to pay more. Everyone pays their own accommodation costs. Grandma is covered by her children and grandchildren equally.

Ok, after your update if I understand correctly, children from age 2-11 are charged full price. That is quite unusual.

If so I understand your unease and I'm inclined to agree with you. Someone has chosen this venue, when there must be plenty of others that charge less for children. Maybe this is not the venue anyone would have chosen if there had not been incorrect assumptions made about who would pay.

As a general principle under the circumstances, I think it would be reasonable to create a "children's rate" , maybe count the big family's children as 3 or 4 heads rather than 6.

I hope the daughter has been firmly put right that it would be unreasonable for her brother to keep covering the whole thing. It was lovely when he could but it should never be an expectation or taken for granted.

If everyone over age 2 is charged then everyone should pay for each person in their group.

“The cost is £x per head for anyone aged 2-100, please confirm who is attending by sending payment asap to my bank account”

People book their own accommodation if they want.
Meal - per head as it was cited by hotel.
Grandma room and accommodation paid for by others. Cost divided between 8 families.
if there are any extra costs - e.g decorations, cake etc they are divided between 8 families.

In my experience it’s better to divide fairly and equally and then if someone struggles people can help each other privately.
E.g my mum would give me money to help with costs in this situation but it’s nothing to do with my cousin so my cousin wouldn’t be involved.

Also minimal amount of alcohol provided plus bar available where people can buy some.

Cost of meals is split by family so the family if 6 kids pay for 8 or 2 x adult 6 x child if kids meals are cheaper. Drink paid for at the bar by each family

cost of grandma and perhaps whatever you use to toast if you do split between each family so 8 families. Accommodation paid for by whoever uses it

Although assuming a retiree is somehow in a worse financial position that a young person with a family is abit 🤔 certainly in my circles it's the opposite way round.

Everyone pays for themselves and equally split the cost for the birthday lady

If the cost is per head then everyone pays what they cost, it's the easiest one ever, you know exactly what each family costs. Split nan between all families, job done.

Is suggest this too

I was more pointing it out to show some people are already shouldering more cost just to turn up.
people would only be shouldering more costs if the family of 3 paid the same as the family of 6? Is that what you mean the family of 6 don’t want to pay for their own food, they want other people to fund them @FunnyOrca ?

I was more pointing it out to show some people are already shouldering more cost just to turn up.

But people’s choices about how many children they have etc., are their choices. Each family needs to pay for their own DC and adults, plus an equal share of their mother/grandmother’s costs.

the cost per head makes it really simple. Everyone pays for their own. Then it’s completely fair. The cost for GM is split between all the heads. It shouldn’t be down for one person to pay for it. People who expect him to are completely CFs.

Everyone pays per head and then granny's cost split amongst the adults. The GC with 6 kids presumably knew that 6 kids cost a lot of money when he planned them

I would split the whole grandma meal by per person, yes even the two year olds plus. That way , everyone has a clear understanding of what to pay and what they can afford. It may seem unfair on the ones that have tiny kids that won’t each much…but it’s a starting and fair point to start on. That way if any grandma/aunt/ uncle wants to help out “ their side of the family” at least you know individually per head what it would cost. It will also help family members weigh up if they want to come/bring the kids/pay for the kids etc

we had years of paying stuff as a family of four , when others in the family may have only paid for two as an example. That’s just what happens in a big family. We’re now a couple paying for two and our kids are paying for their family of four…it just the way of the world. Albeit as I’ve said you might get an uncle or grandad in the family who may pay “for his side “….my husband often pays for our adult kids and grandchildren’s fee per head in cases like this. But breaking it down per person including everyone “eligible “ to pay makes it fair and clear.

with regards to anything else, like accommodation etc let everyone sort out their own

I would split the cost of party/catering per head. If anyone can’t afford it, then they need to speak up, but I wouldn’t assume a retiree is in a worse off position than a 25 year old.

Accommodation split by room by those who need it.

Accommodation - each group pays their own

shared costs - divide among all adults

Adult children/grandchildren split the cost of the function room and the buffet/catering between them.
If it is individual meals, each adult pays for their own and their own family unit

Whoever wants accommodation pays that separately, just as they would if going away separate to the event