Reverse the order - girls upstairs last?

What if MM/KG were actually killed last not first? I know the widely accepted narrative is he started upstairs then went down, but what if you read the evidence with the viewpoint it happened in reverse order? What evidence now supports that narrative?

Here are things that come to my mind:

• Dropping the sheath in MM’s room AND supposedly leaving bedroom doors open - suggests he left those rooms in a hurry
• KG’s dad saying early on that the killer “didn’t have to go upstairs”
• DM close to the time she saw man leaving texts KG asking what’s going on and calls her - maybe because last noises or struggles that she heard were all upstairs? Then DM flees from her room downstairs - maybe thinking that’s AWAY from the perceived upstairs threat?
• Wasn’t the dog heard barking towards the end of the commotion shortly before BK’s car flees quickly? Wouldn’t that mean BK was in closest proximity to Murphy at the end? And his barking spooked him into thinking the cops were about to be called?