Scan no more than 6 kids into the sleigh - the rotation of names has a max of 6 names to the list before it bumps one off, and accepts a new in it's place.
If there are more than 6 kids they may or may not see their name
If someone really wants to see their name and they haven't seen it, have them scan the card again
Additional context: ideally groups have no more than 6 kids, knowing that is not always possible based on traffic. When there are 6 or more kids, each kid should scan and enter the sleigh as soon as possible. If you scan all at once and then move all the kids in at once you run the risk of kids missing their name.