Major Description
The main problem is that, due to return path, now we may have (RS1-GBY2)-(RS3-GBY4) when map.aggr=false, i.e., no map aggr. However, in the non-return path, it will be treated as (RS1)-(GBY2-RS3-GBY4). The main problem is that it does not take into account of the setting.
