Most name-list problems come from how names are collected, not from the airline. Here is a method that works for groups of any size.
Use one shared sheet
A spreadsheet beats chat messages and emailed photos. Columns: first name, last name (both exactly as on ID), gender, date of birth, ID or passport number, passport expiry (international), mobile number, meal or assistance needs.
Copy, do not type
Ask each person to copy their name from their ID card or passport — not from memory. People who use one name day-to-day often have a longer name on their documents.
Set your own deadline
Close the sheet at least three days before the airline's name deadline, then have one person check every row against the IDs.
Protect the data
Passport and ID numbers are personal data. Share the sheet only with the people who need it, and delete copies after the trip.
Quick answers
Do you need ID numbers for domestic group flights?
Names, gender and age group are the essentials; some airlines also request ID details. For international travel, passport details are required.