How could I add existing levels to a World via Python? This is my most recent attempt:
loaded_level = unreal.EditorLoadingAndSavingUtils.load_map(level_path)
if loaded_level is not None:
world = unreal.EditorLevelLibrary.get_editor_world()
unreal.EditorLevelUtils.add_level_to_world(world, level_path, unreal.LevelStreamingAlwaysLoaded)