Don't mistake returning a plate for indicating the vehicle they were once attached to was sold - they may put that in the computer as a reason for surrendering the plates, but that doesn't automatically cancel the ownership of the vehicle they were attached to - it's entire possible to take a vehicle off the road, return the plates, and still retain ownership of the vehicle.
Informing the MTO of a sold vehicle (in the scenario here where one isn't sure the new owner is going to properly take over ownership) is a whole different process.
Informing the MTO of a sold vehicle (in the scenario here where one isn't sure the new owner is going to properly take over ownership) is a whole different process.