I can’t help, but I can give my experience on time-zone adaption.

It depends on the individual, but (based on my attempts) there’s not much you can do to get a kid to just go to sleep earlier (especially if they have a reason to stay up late). So all I can do is have work on the waking-up time.

Pull back the waking time a little earlier each day (30 minutes or so, but not more than an hour earlier a day). Start with 8 hours from their current sleep time, even if it’s they’re currently going to sleep at 7am (which is typical if arriving in the UK from the west coast). Aim for a sliding window of “acceptable sleep time” that’s 8 hours or so and try to pull it back each day.

Outside of the bedtime hours, random naps may happen while trying to adapt, but don’t let them last too long. Maybe 90 minues, since that’s meant to be the deep/light sleep cycle. Too often I’ve been fooled, thinking “Great! The kids are asleep by 1am! Progress!” only to have them wake up 3 hours later and be up until 9.

You get the occasional relapse too (although usually in the first few days) were you think everyone’s adapting and then someone just flakes out at some random time, but I just try to keep to the sliding bedtime window as best I can.

Should have called it “climate instability” or “climate chaos” from the start.

How do you feel about ducks?