I had successfully done it recently on my journey to Rajasthan in May-2015 with a lot of hustle n tussle.
Mine was ticket booked as Handicapped and my son was booked as escort. Due to his exams he was not able to travel with me, so i decided to take my wife as my escort. So i request a name change for SON to MOTHER.
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I...
more... approached Chennai Besant Nagar PRS with all necessary documents and xerox. after almost 15-20 min of his best effort with computer he declared that name change for Handicapped ticket can not be done. I had a argument with him that can you show me any rule which shows the same. He answered - As system is not accepting this, it can not be done.
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Next step - I went to CRS at central station PRS, who also sang the same tune..... Finally I decided to meet ACM/ Reservation in 2nd Floor at Moore Market Complex PRS.
Chief Reservation Supervisor / Administration was on duty there. He listen my grievance and made a solution in one moment. He said Name change in ticket booked with handicapped concession can not be done in system but it is permitted manually with full description endorsement on ticket itself. Within 5 minutes he made all endorsement and my work done. I also told him to inform CRS who are not aware of this rule to save passengers from harassment (as this case belong to handicapped passengers, for whom running from pillar to post is very very difficult)......
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I will post the pic of ticket later with endorsement....