Hollie Brueggemeier

Ok, so let me get this straight...they had a daughter and she died years ago so these parents PRETEND they still have a daughter? So they are nuts then?? So many odd twists and turns and why all the killing? Did they fake their dead daughters disappearance and needed to blame someone so they killed the other married couple next to them??? I am so confused. And why dead dog?? Horrible movie.