U simply can do 2 things:
1. Rebook, while chance again is dim, as for Garib/Raj/Shatabdi/DRNTO, they go on Coach filling, even whn other Coach is totally empty & do have LB..
2. While train parked @ SC, check chart @ Coaches & u may find 1 or 2 Coach with least occupancy or mayb quite empty!! Switch to the concerned Coach, if u find some such Coach!! Have done it many times, while on-board DEE-YPR DRNTO & YPR-PDY GR recently, with 100% success rate & Coach with 10-12 Passenger Occupancy FTD!!