How to divide accommodation cost

[Holidayhouseone]

I know we love a holiday house one and how to fairly divide cost and rooms !
1 house 4 nights. 1 couple only coming for 2 nights.
Rooms are pretty easy as they're all the same except for a twin my children will share and our friend's DD will have a room to herself.
Now to cost- I was thinking of dividing cost by rooms per night taken by family- does that sound fair? Although there will be a spare for 2 nights !
Or do I work it out per person and for the 2 nights where there's 2 nights the families there for all it it need to cover the cost?
I think (hope) we all like a bill/ room
allocation / cost share thread? Thanks!

If I understand you it there are 2 families?
Your family staying 4 nights?
Other family staying 2 nights?

Total cost/total nights=nightly rate
Your family pays first two nights
Both families split cost 50/50 for remaining two nights.