If God has a sufficient reason for permitting evil in some possible world then he has a sufficient reason in all possible worlds. Given simplicity, God is perfectly similar in every possible world we can conceive. He never wills differently, he never acts differently, he never knows differently, and he never loves differently. If modal realism is true and evil exists then the probability overall or on balance for justice is precisely 1. Thus, the problem of evil is an insufficient objection given whatever God’s interaction is in this world. It would be morally equivalent to his actions in other worlds with evil. If God is absolutely similar in all possible worlds and if he has a morally sufficient reason to permit evil in some possible world then he is morally justified in permitting evil in all possible worlds (even if some worlds are more bad than good because God would be acting towards the same telos). The following is a modified version of Alvin Plantinga’s ontological argument. In it I include the necessary entailment of a morally sufficient reason for permitting evil.
P1. The property of being maximally great is exemplified in some possible world.
P2. The property of being maximally great is equivalent, by definition, to the property of being maximally excellent in every possible world.
P3. The property of being maximally excellent entails the properties of omniscience and moral perfection.
P4. The property of moral perfection necessarily entails a morally sufficient reason for permitting states of affairs that are overall more evil than good.
P5. A universal property is one that is exemplified in every possible world or none.
P6. Any property that is equivalent to some property that holds in every possible world is a universal property.
C1. There exists a being that is essentially omniscient and morally perfect.
C2. There exists a being that has essentially morally sufficient reasons for permitting states of affairs that are overall more evil than good.
 This will function in the same way the ontological argument works. If it is possible for God to exist in some world then he exists in all worlds. Similarly, if God is simple and absolutely similar in all worlds then if he has a morally sufficient reason for allowing evil in some possible world then he has a morally sufficient reason for allowing it in all possible worlds.
 Robert E. Maydole, “The Ontological Argument” in The Blackwell Companion to Natural Theology eds. William Lane Craig and J.P. Moreland (Oxford: Blackwell, 2009), 573.