Well...this is a whole question of 'is there free will or not?' then, isn't it? And as I've never been able to answer that question here in real life, I can't very well answer it for Middle Earth. I think that Eru is Tolkien's character for God, and so that whoever thinks that there is free will here on Earth will think that there is free will in Middle Earth, and those that believe God handles everything and no one has any free will here, will think the same for there.
So, unless it says otherwise, somewhere in the many histories of that world, I don't know if there is a real answer to this question...just a matter of opinion.
I have no answer.
