We moved to the UK last year with our then 13 and 15 year old.
We did a secondment first, so they could see the place and that helped.
They did find it hard, leaving their friends and schools, leaping into the unknown.
We did a fair bit of bribery and corruption, that helped (new mac-books)! And of course, all new bedroom stuff.
We didn't expect them to be happy about it, we let them have their feelings, express their feelings, and empathised and sympathised with them. While saying, however, this is the way it is going to be, there is no going back, so we all have to make the most of it.
The 13 year old found it hard to commit to the new school, and to try and make friends until she accepted that this really was it. It didn't help that her 'friends' back in NZ basically dumped her, not including her in their online chats.
There have been good days and bad days. There have been tears, there has been anger, but now, I think they'd fight us every step of the way if we said they were going back to a Kiwi school. They're excelling at school, they've made good friends, have good friendship groups, have enjoyed experiences that they would never have been able to dream of back in NZ.
We said it would be at least two years before we went back to NZ, even for a visit, so that everyone would be very settled. We go back next year and it will be interesting to see how they go. They're very different people to the people they were, and a lot of that is down to having done this. They're a lot more mature, poised, focused and self confident.
Oh, and do try to plan some awesome holidays to look forward to, in your new country. Ask your daughter where she'd love to go in the States, and plan a holiday there if you can.
Good luck to you all!