So either the backpack etc did not belong to Danielle, or it would indicate she might have been grabbed at/after the school, before she ever boarded any motorized conveyance that Friday afternoon?
Do we have any proof that Danielle ever got home from school that Friday?
I think this was the shopping trip/passport pic day and Bren took them out of school early. I could be completely wrong on this so maybe someone else will remember better!