I am bringing documentation. Will they definitely let us pre-board with our daughter (age 7 ASD) and other 6 year old (has other health issues)? We are flying Southwest. I keep hearing horror stories of 5 year old kids not being able to sit with their parent because people don't want to give up their seats. I am very nervous about this happening. Pre-boarding would help because our daughter does not like to be on line with tons of people all around her. And then I would have a minute to wipe down all surfaces with clorox wipes for our other daughter. What should I say to make the SW person understand?