All trains which have long TAT and undergoes SM/OEA at BGP are the most likely candidates for extension to Godda. BGP - AII is also one such candidate( once maintenance facilities are available).
From JSME: JSME - VSG & JSME - PUNE are the likely candidates for extension. JSME - SMVB & JSME - TBM can only be extended if ASN agrees to do away with their PM.
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A new Godda - Mumbai weekly can be introduced either via - DUMK, JSME or via - BGP.
ST - MDP weekly can be introduced with extension upto Godda/Dumka.
But, DUMK should be developed by ER - ASN division to handle SM/OEA. If it happens, we might see some of the above trains extended till Dumka instead of Godda.