I have to admit that I have never needed to do this before! We will be driving to WDW in September. Because my family of 6 had to book two rooms, we will have an extra bed. I would like to invite my sister and her DD (9) to join us for a couple of days as there would be no extra charge for them in our room(s). Anyway, I would like to go ahead and book her flight so she can't say no! What is the best and most economical way to go about doing this? She would depart from either Charlotte or Greensboro.