I'm Canadian and although I'm no where near applying for residency I do know that there are residency programs that sponsor you. Post grad in US for internationals is getting tougher and tougher to get into each year with the number of american grads increasing in the carib and domestically, plus the DOs grabbing a lot of allopath spots.
To the best of my knowledge relatives don't help in any way unless he has an immediate relative (sibling, parent) who can sponsor him for a green card, but that takes many years. And no, it won't help him in any way to finish post grad in India, except it might help him w/ the steps.
That's all I know, check the Canadian IMG section for more info.