Good Luck! I don't think they have thought this through properly. A wedding abroad is not the most important thing to get to IMO.
Sometimes people are quite glad of an excuse to pull out.
4 days and nights is a long time, especially as the parents will be out of the country.
My DGD became very sick on her first sleepover with us aged 10 months and had to go to hospital.
It would be no from me. Unless of course they take you with them as babysitter?
Honestly, my house is such a mess
What sounds remind you of your childhood home?

