docs: def add_resourcegroupitems(scenario_id, items, scenario=None, **kwargs):
  
      """
          Get all the items in a group, in a scenario.
      """
      user_id = int(kwargs.get('user_id'))
  
      if scenario is None:
          scenario = _get_scenario(scenario_id, user_id)
  
      _check_network_ownership(scenario.network_id, user_id)
  
      newitems = []
      for group_item in items:
          group_item_i = _add_resourcegroupitem(group_item, scenario.id)
          newitems.append(group_item_i)
  
      db.DBSession.flush()
  
      return newitems