I love this topic. I think the answer is simpler than we allow and the answer is 3 (stay with me my sanity will become evident in a minute.) We know that the number three has powerful implications in our species. Our brains are wired to remember things in three's ( why we say bad things happen in three's). We know that in many religous belief system things are also presented in three's. We know that a woman(1) and a man(2) result in a baby (3).

So the answer to "destiny" and "freewill" is most likely explained in the same manner. Think of a human's existance and relationship with god(s) in the same terms as parents and child.

Born of the parents the child's life is the result of three different conditions; determination, divine guidance, and randomness.

A child is born with certain "things" which will ultimately "determine" other things. In this way there are aspects of their life that are predetermined at birth.

Like a child grows partially through the guidance of his parent(s) so too is there a divine guidance that leads each of us to certain choices and paths.

And third, there is the apparent randomness of events both created and experienced that will provide unique opportunities to make choices that ultimately lead us to a place..and those choices are many, although not infinite as some are removed by conditions one and two.