[Edit Ran out of characters left to type)]: One more thing: you can track all the instances of the boxes in a level blueprint by adding their instance ID to an array. To get the ones already spawned, just use [GetAllActorsOfClass]. To spawn, use [SpawnActorFromClass] and store the resulting ID in the array. Alternatively, you could use the new instance ID to bind its [Overlapping] events to a function in the level blueprint.