According to your theory if say for example: DHN-ALLEPPY is given full rake then its slip TATA- Alleppy slip should be cancelled? It cannot be done na...DHN-ALLEPPY and TATA-ALLEPPY both should be given full rakes...in that case existing TT of TATA-Alleppy exp needs to be completely changed na...and for that slot availability from Tata to Alleppy needs to be available na. Similarly, there r many such Slip trains in IR whose totally new TT and Slot is required.
On DHN-Alleppy exp full rake discussions expected in IRTTM 2020.