God may or may not have a divine purpose for the unborn. I won't speculate on that (nor should I). That is besides the point. To agree that, "God deliberately wanted the 11 year old girl to conceive her grandfather's child" is kind of unfathomable.
If that is your point of view and minset, wouldn't you also say that "God deliberately wanted the Romans and Jews to beat, whip, torture, crucify, etc... the Savior Jesus Christ?"
I guess we can agree to disagree. I don't think God wanted His [imperfect] children to torture and crucify His only begotten son Jesus Christ... Having said that, I do believe God allowed man to do that to His son Jesus Christ for the chance that mankind might be saved (aka the atonement). Similarly, I don't think God WANTED the 11 year old girl to get pregnant, but allowed the grandfather to impregnate her. We know the cause-and-affect of sex, we know the blessings and curse of "free will"... God allows things to occur, but I wouldn't say he WANTS them to.