If u want extension then rerouting should be der and it is not possible so no need of extension..
Already trains like udz - njp , kavi guru, gareeb nawaz etc are der for jp , udz, ajmer,
And avadh assam is der for bkn ..
And if u want trains from ju , barmer, jaiselmer then u can take train to...
more... jaipur and board from der .