At the counters, you can well avail of this facility.
Fill up the upper section of the reservation form with the first train ‘from’ Jammu ’to’ Howrah with ‘reservation upto’ Delhi with the journey commencement date from Delhi.
Fill up the Lower section of the reservation form with the second train ‘from’ Delhi ’to’ Howrah with the date of journey required.
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more... Because of unawareness, a counter clerk may tell you that you are asking for something impossible. Do not get disappointed and try try to convince else deal with the Supervisor / other counters.