The Problem of Non-Evil

Is the standard notion of heaven self-consistent? Can you have both the necessary freedom from suffering and freedom of the will for those in heaven? If you say that there is no suffering in heaven because the only people allowed in are those who would never choose to inflict it, then it is not necessary, but contingent. There could be suffering in heaven, but there just happens not to be because of the choices. On the other hand, if God can guarantee it, say, by over-ruling or correcting for free choices that would inflict suffering on others in heaven, then it surely is a much less robust notion of free will than we would want. There is no corresponding problem with the concept of hell, because we could strip away free will or not and still have plenty of suffering, but with heaven we seem to have a concern. So, can the freedom of the will and freedom from suffering be reconciled in a way that saves necessity?