You do make some good points Sara and I hope I've addressed them further in the fic.
I think part of the point is that if they go back and cause the accident, are they *sure* what will happen? Or could they end up somewhere without E/L/D *or* C/N? I'd have a hard time making that choice and I don't get a long particularly well with most of my family, but having to choose between my dad/sis and my kids in a life or death situation would be very difficult. My kids would win but I'd still have serious guilt and other issues to deal with.
Part of it at least is addressed in 30. Please let me know if you think it needs more...
Carol