She's probably a lot more than $6k upside-down on the van.
The dealer wanted $6K to even hope to get financing. Most lenders won't lend anymore than 15% of the purchase price of the vehicle. So, it's possible that the $6K was just needed to get the upside-down amount under that limit. She could be more like $10K upside-down. It's possible with the way some people trade cars like they do thesedays.