I'm really confused why you would maintain insurance on a vehicle you don't own. I'm surprised your sister was able to get another insurance policy for the vehicle. Normally a second policy won't be issued for the same vehicle anyway. But if she purchased it recently, she may get something in the mail soon saying that her insurance policy has been cancelled since there was already an active policy in effect. Or you may get a letter cancelling your policy. Or both. You're treading on dangerous ground here...