Nearly two thirds of people planning group travel name coordinating schedules as their leading stressor, ahead of budgets and ahead of comparing options.
The reason is that one person ends up holding the whole thing in their head, and that person is answering the same four questions repeatedly for two weeks.
Decide these three things first
Almost all group travel friction comes from leaving these implicit.
3 things to do
Ticks are for this visit only. Nothing here is saved anywhere.
The four questions you will be asked repeatedly
What time are we leaving. Where are we staying. What is happening on Thursday. Am I on that booking.
Every one of those is a lookup rather than a decision. If the answers are readable somewhere, the questions mostly stop, and the ones that remain are genuine decisions worth your attention.
Record who is on what
In a group, a booking is not simply an event. It is an event with a subset of people attached, and that subset is rarely everybody.
Four people on the flight, two on the car hire, three at the restaurant. Writing that down once answers a large share of the questions above and prevents the specific problem of somebody discovering at the airport that they were never on a booking.
Note what each person needs
Dietary requirements, mobility needs, a seat preference, medication that affects timing. In a group these live in several heads and surface at inconvenient moments.
Recorded once against the person, they are available when a booking is made rather than remembered afterwards.
When something moves, it moves for a subset
This is where group trips get genuinely difficult. A delayed flight affects the four people on it and not the two who travelled separately, and working out who needs telling is its own task.
Knowing what depends on what is the same skill as in any trip, covered in what else your trip depends on. The group version simply adds the question of who is affected.