1. There exists only one RL for a single train. However different remote stations can have their individual share from the originating station.
2. In this case, it is clearly evident that the RS Quotas have been merged with the GN Quota. Reason can be less number of coaches=> less number of berths=> more reason of linkage with one another.
Kindly go through the below data:
1)
Kolkata Sealdah/SDAH to Guwahati/GHY
General Sleeper AC 3-tier AC 2-tier
2012-03-01 Avbl 145 Avbl 59 Avbl 12
2)
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Kolkata Sealdah/SDAH to Malda Town/MLDT
General Sleeper AC 3-tier AC 2-tier
2012-03-01 Avbl 213 Avbl 81 Avbl 27
3)
Kolkata Sealdah/SDAH to New Jalpaiguri/NJP
General Sleeper AC 3-tier AC 2-tier
2012-03-01 Avbl 189 Avbl 73 Avbl 22
4)
Kolkata Sealdah/SDAH to New Alipurduar/NOQ
General Sleeper AC 3-tier AC 2-tier
2012-03-01 Avbl 154 Avbl 61 Avbl 15
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It can be seen that SDAH-MLDT has more share when compared to start-end, i.e. SDAH-GHY.
Also, SDAH-MLDT having the max share=> Max limit for General booking. Since the number of coaches is less, all these stations has share from the originating station.
General Sleeper AC 3-tier AC 2-tier
2012-03-01 Avbl 145 Avbl 59 Avbl 12
On top of this, they has their abovementioned share. Subtract 1, from 2,3, and 4; you would get their individual share. This share is totally specific to the concerned stations and can be utilised for the specific journey leg as discussed above. ( I havent checked thoroughly, their can be other journey legs coming under the same quota).
After both the share gets exhausted; i.e. base quota+individual quota, they are all merged into a single common WL.
Now kindly see another set of data:
1)
Malda Town/MLDT to Guwahati/GHY
General Sleeper AC 3-tier AC 2-tier
2012-03-01 Avbl 16 Avbl 4 Avbl 5
2)
New Jalpaiguri/NJP to Guwahati/GHY
General Sleeper AC 3-tier AC 2-tier
2012-03-01 Avbl 31 Avbl 8 Avbl 4
3)
New Alipurduar/NOQ to Guwahati/GHY
General Sleeper AC 3-tier AC 2-tier
2012-03-01 Avbl 9 Avbl 2 Avbl 1
##
Conclusion: Less number of coaches=> Less quota=> More chances of linkage of RS with GN=> More chances of confirmation of the WL'ed tickets from the intermediate stations. As you correctly said, the 3 stations have different charting points of their own and hence maintains their individual WL.
However do not confuse for the existence of RLGN when RSWL is not displayed. RSWL is very much here, however due to some reason/s, it has been merged with GNWL!!