How to devide holiday bill

[Dithercats]

Situation is holiday booked and paid for by me. Invited 1 adult to come with me & kiddies. Price per person £1000

2 adults.
4 children
2 free kids places.
Total £4000

How much would the adult friend needed to pay?

£1000 price per person? So I then pay £3000
£666 price divided by all 6 holidaymakers? So I then pay £3333

Which is fairer?

Thanks

I like this option best too, and hadn't thought of it so thank you. That's what I'll do.

Sibling will do whatever, I just wanted to do the right thing , whatever that is.

We are all really looking forward to it 😊