Group A have booked a holiday cottage for £2000 for 10 nights. 2 adults.
Group B are staying for 3 nights 2 adults and 1 child.
Group C are staying for 4 nights 2 adults and 3 children.
One way to split cost would be per person per night so overall there are 49 ‘person nights’ which you could price at £40.82 each so A would pay £816.40, B £367.38 and C £816.40 as well as there are 5 people in group C but for fewer nights?
Or could split by rooms - A will use 1 room, B 2 rooms, C 2 rooms plus sofa bed in communal area?
Or is there a simpler way we’re not thinking of?