Young couple goes on van tour of US, boy comes back with van - no girl

So not quite right on that. A&A happens before the crime, accessory (after-the-fact) happens after.

https://www.findlaw.com/criminal/criminal-charges/aiding-and-abetting-accessory.html
OK so does the latter carry a "heftier" sentence?
I guess what I would look for is leverage LE has to get the parents to cooperate (if they simply are not providing LE with everything)