There's a lot of theories about who really escaped deaths grasp in the Final Destination movies. It is confirmed that Kimberly Corman and Thomas Burke, from Final Destination 2 survived. Confirmed in the Final Destination Bloodlines.
The big discussion nowadays is if Wendy, Kevin and Julie survived the train derailment at the end of Final Destination 3.
Note that these characters had no interaction with Mr. Bludworth, which could explain that he had no idea that these people even existed. Another reason that he didn't know could be because he was a coroner in the State of New York, where Final Destination 1 and 2 take place in. Final Destination 3 took place in Pennsylvania.
Wendy and Nick (Final Destination 4) are the only characters in the series to ever have 2 premonitions of catastrophic event. Julie having one of the roller coaster, and the train. Nick having one at the speedway and the mall. Nick stopped the mall explosion after having the premonition, so we could assume that if a character has a premonition about an event, that they absolutely have the ability to stop it.
I'd like to think that Wendy, Kevin and Julie stopped and survived the train wreck. They did deserve to survive, but I also know that it is a possibility that they couldn't stop it, since we heard crashing noises at the end of the movie, but the director made it that way on purpose to drive us all mad thinking about it.
What do you think?