SWV is not in Goa it's in Maharashtra and all the trains you are saying to get extended are exclusively for connectivity to Goa.
If SWV is underutilized ask CR of your beloved KR to run dedicated trains from there why snatch trains from Vasco ?
Then the three trains you mentioned have only 3 hours of TAT at VSG then they return back so why should SCR give additional rake and extend to SWV ?
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Also MAO to SWV is single line and SWV too lacks necessary infrastructure for maintenance which VSG has. Why saturate the already saturated single line of KR ?
Why should 1 lac plus Vasco people sacrifice dedicated rail connectivity to Hyderabad and Tirupati for the places in Goa ?
Why don't you ask your beloved KR to extend some Gujrat and Mumbai trains from MAO to QLM ?
These trains serve North Goa and only one city in South Goa ie MAO extending to QLM will serve the population in Sanvordem and Sanguem too.

There are terminal constraints at Vasco because of only pitline and second pitline SWR can commission whenever they want and run more trains besides these SCR trains of Tirupati and Hyderabad don't require pitline maintenance at Vasco so no need for you to panick. They just occupy PF #2 for 3 hours thrice a week and leave.
The earnings of VSG which I have put up in previous post don't justify your nonsense of trains running 90% empty from VSG.
The 1.5 lac population of Mormugao Taluka (2011 data) does justify the trains VSG gets you don't have to put up nonsense like VSG is less populated because people may lie and have biases but government data doesn't.