So the car was never formally transferred in the present owner's name. The plot thickens. So let me get it right. Mr. ABC booked the car, Mr. XYZ was the first owner and now this guy, Mr. JKL has a sale deed on a stamp paper from Mr. XYZ? Is that right? What stopped him to transfer the vehicle in his own name? Seems fishy. Of course he will say, he takes full responsibility of the docs. God forbid if something goes wrong, his guy, Mr. JKL will be no where to be found. Plus if he was such a respectable/honourable citizen he would have done the right thing and completed the transaction by transferring the car in his own name.
What is to be gained by not transferring the vehicle to the second or third owner. The only thing that comes to my mind is to falsify the car records to show it as a first owner car. Sir, I think you should move on to another car if having right docs for the car is important to you.