Yes just put your dash or vin in another car is illegal. But if your car is made up from 2 to 10 different cars which one is the original?
Some cars are pretty ruff.
Say your restoring a car the front is solid and the rear and the roof is rotted. So you rear clip it the now the car is 50/50 two cars but since the dash belongs to the front half its that car ?? But say now it's the opposite your car has a perfect rear and you front clip it from the window post to where the rocker meets the rear door jam. Now which car is it ? And if you bought the front clip from a wrecker and has no dash or ownership or if you got it from a car that's a donor car that does. Does that make a difference??
What parts do you exactly need to go with the vin to be original ?