Trip Mode is on Plus and Premium.
The trip
Give it a name, a start and an end. Those dates do real work: the calendar marks them, and an itinerary item can't be filed outside them, because a plan for the day after you fly home is a plan you won't keep.
Packing
Each traveller gets their own list. Not one shared list with names beside the items, which is how a coat ends up in nobody's bag.
The itinerary
Add flights, check-ins, bookings and plans against a day. Anything with a time on it appears on your calendar and alarms thirty minutes ahead.
Those calendar entries aren't copies. Move the trip and everything moves with it. Delete it and they go. Nothing is left behind pointing at a week you're no longer traveling.
Sharing it
The link carries the days and the times, so everybody coming knows where to be. Packing lists never go on it. What is in your bag is nobody else's business, including the people you're traveling with.