A fairly standard libertarian response to the question about how people can freely choose right over wrong in heaven is this: They have a morally perfect character that makes them unable to choose wrong but this character is the result of choices in this life, choices that they could have avoided. Thus, the choice of right over wrong in heaven is derivatively free, with the freedom deriving from non-derivatively free choices in this life. For a nice development, see Timpe and Pawl.
I had a student ask the question how this works for those who as small children and who hence have not developed their character through free choices. Multiple answers are possible, but I wanted to offer one that yields a somewhat interesting theory of limbo. The theory of limbo holds that some people--those who die in infancy are often given as an example--have not had the kind of life of faith that is required for heaven but nonetheless have done nothing to deserve hell. They are, thus, in limbo: a happy state that, nonetheless, falls short of heaven.
Here, then, is a theory of limbo. Limbo is very much like heaven. In fact, those who are in limbo are a part of the same community as those in heaven, and there is no difference of location, but only of state. Those who are in limbo enjoy most of the joys of heaven: the beatific vision of God, union with wonderful people, flourishing human activity, etc. Their lives are very much like the lives of those who count as being in heaven. However, their choices of right over wrong are not free, because although they have the same morally perfect character that those in heaven do, in the case of those in limbo, that morally perfect character is not the result of their own free choices in this life--it is simply imposed on them by God. So they don't have the joy of knowing that these choices are free, and they don't have the joy of remembering how they freely formed their character, but otherwise they get to enjoy all the joys of heaven.
On this theory, it is better to be in a heavenly rather than limboic state, but the main joy of heaven--the beatific vision--is equally had by people in both states. The difference is solely that those in the limboic state lack the derivative freedom that those in the heavenly state have.
What I don't like about this theory is this: I have the intuition that God shouldn't force people to love him. But perhaps I should simply say: it is better to love freely, but loving unfreely is still good?