def METHOD_NAME(
    self, world_name, tree, volume_manager, volume_engine
):
    sorted_actors = sorted(self.actors.values(), key=lambda d: d.user_info.priority)
    for actor in sorted_actors:
        if "SteppingAction" not in actor.fActions:
            continue
        # Step: only enabled if attachTo a given volume.
        # Propagated to all child and sub-child
        # tree = volume_manager.volumes_tree
        mothers = actor.user_info.mother
        if isinstance(mothers, str):
            # make a list with one single element
            mothers = [mothers]
        # add SD for all mothers
        for vol in mothers:
            vol_world = volume_manager.get_volume_world(vol)
            if vol_world != world_name:
                # this actor is attached to a volume in another world
                continue
            if vol not in tree:
                s = (
                    f"Cannot attach the actor {actor.user_info.name} "
                    f"because the volume {vol} does not exists"
                )
                gate.fatal(s)
            # Propagate the Geant4 Sensitive Detector to all children
            n = f"{world_name}_{vol}"
            if world_name == gate.__world_name__:
                n = vol
            lv = volume_engine.g4_volumes[n].g4_logical_volume
            self.register_sensitive_detector_to_child(actor, lv)