I've found the towing company that took care of this family's van. They're in Alexandria, about 20 miles up the road. And, I'll be leaving the van there for at least a few days: the odds are that an insurance adjuster will want to see it.
My wife tells me that the van is noticeably shorter now, than it was yesterday at this time.
The good news is that #3 daughter's backpack and guitar aren't in the van - and we know where they are. The guitar's in a soft case, and stands up when leaned against the wall, so I'm hoping that it's relatively undamaged.
Now, I've got to work out how to recover what we still have inside the vehicle, and what to do with what I suspect is now more a source for spare parts, than a repairable vehicle. That'll take time. And, I've been assured that there will be forms to fill out.