Phage

Nope. Look at it this way; how can humans have free will if God's plan cannot be affected by humans? A recurring theme in the Bible is someone pleading the case of someone else who is clearly guilty of some transgression (e.g. Jesus), which allows forgiveness.

Free will requires that you be able to direct your own actions, and a plan that in unable to be affected would make that impossible. A lot of people have a hard time reconciling free will with omniscience, so I will give an example that contains all these points.

Suppose I am a parent, and there are two children under my care. One of the children has stolen a piece of candy, an action that requires punishment. Being at fault the child is not in a good position to request forgiveness. However, the second child steps forward and pleads the first's case pointing out that he is truly sorry and willing to make amends. With this I am able to "change my mind" and forgive the first child.

Note that I could have known all of those things with a certainty; the theft of the candy before it happened, the fact that the second child would plead the first's case, and my ultimate decision. Omniscience, a plan, and free will are not contradictory.