When you do partial cancellation of tkt, system re-assigns the lower berth and only cancels the upper and middle berths as much as possible. That is the system functionality
I am not sure if you have an option to tell the system as to "I know what I am doing, please do not apply your newfound intellengence and force it upon me"
In other words, if you have UB and LB in a single tkt and you decide to cancel tkt of the person who has been allotted LN, system will cancel the...
more... UB and reassign the originally allotted person of UB to LB. This works fine for most of the case, but what if I wanted UB by choice. There is no way to tell the system that