Well there is some truth in that theory alatar, as if I remember correctly Gandalf does say something like: not many except you would have made it so far. Not sure where, not going to look for it.
But I doubt that Eru would go so far so as to do any other changes other then pushing Gollum in.
Indeed I have already had many discussions about luck, fate and providence in M-e and I although it seems to be more then just a coincidence I personally can't believe that Eru would "play" in such a way with the inhabitants of Arda.
What god of love would kill two innocent hobbits, no matter for what purpose. And would Tolkien as a believing Catholic write such a thing? I doubt he ever intended such a thing, however it could be seen as just a chance event as all others. But then again we can go further back in past and maybe speculate that the sparing of Elros and Elrond was also planned by Eru, as no Elros and Elrond meant no Aragorn and Arwen and Fellowship and succesful Quest.
This problem is unfortunately not easy to solve...