I learned.this.... a family only needs ONE form...
First question - Are traveling alone ?
List all family members on one.........
Up to six people can be added on one E-Ticket unlike the paper version which requires one (well, more than one form for each) per person. Most families have less than six people, so for those travelling as a family one E-Ticket will do.
The moment your passport is scanned they can see on their computer screen your E-Ticket information, name, address, flight, visas, etc. That's the reason they don't ask as often to hand them an itinerary of your flight, they can see it on the screen.
It's similar to prtially filling a form online and then not proceeding. If you already put things such as your email, it's not required to press the "send" botton for them to get it. In fact, that's the reason you then get junk mail from a site where you didn't submit the information and only filled a part of it.