Better come with some feasible demand. A train from NDLS to DHN via PNBE sounds too illogical. Moreover in ECR,PNBE deserves a dedicated SF train for Delhi more than any other city. Regarding Vaishali too,SHC KGG DMH and whole Kosi region deserve a daily train for Delhi more than BJU..SHC deserves more than BJU..Go and check revenue (passenger) generated by both stations and number of passing trains.