Assuming the cops did a thorough search to eliminate the possibility of the family’s car falling into the river during the fog, then it’s likely Christmas Eve host family who “disappeared” the victims. I don’t think the family could suddenly decide to move away without telling anyone (why would they-they weren’t in trouble), so if they’re not in the river then it’s the other family who were the last to see the victims. Couldn’t they search the host family’s property (though after 50 years there likely wouldn’t e any useable clues)?
Thanks for bring us this great video. In the recording, i felt like jacques' friend couple are hiding something from the police. They maybe murdered by the friend couple. They burned their car and along with their bodies, they melted in the iron burner.