I read that they did change certain things and wonder if how they found each other was one of them. It just seemed a bit twee and contrived. I am not sure how todo spoilers so I wont ask my question but Iam sure I spotted a big continuity error
But even so fantastic film and very well done
They did use some artistic licence for how they all got together. From memory, I think the scene where he sent the kids away in a truck was changed because they were really just on the roof of the chalet the family stayed in, but he apparently did leave them there to go and search for his wife.
So it would consequently make the scene where the brothers met up on the truck also not quite accurate. Even though that scene itself just made me cry like the big sissy girl i am