Hi. We leave in 13 days for our vacation. It's been awhile since we've flown Southwest. We didn't book the early-bird check in. I plan on getting online at exactly 24 hrs prior to flight and have someone do the same while we're away. Can you explain the boarding groups and numbers? Do people just place themselves in line in the right numerical order???? Just hoping that we each get to sit with one of our kids, especially, the 9 yr old who has trouble with his ears when we fly.