Info about de-reserved coaches in M/E trains for season ticket holders:-
----------In train number 16382 Kanyakumari-Mumbai CST Jayanthi Jantha Express, coaches S5, S6, S7, and S8 are de-reserved between Kanyakumari and Ernakulam and coaches S9 and S10 are de-reserved between Ernakulam and Palakkad Junction.
--------------In 16525 Kanyakumari-Bangalore City Island Express, coaches S3 and S4 are de-reserved from Nagercoil to Ernakulam and coach S12 is de-reserved between Nagercoil and Palakkad.
-----------------In...
more... 16329 Thiruvananthapuram-Mangalore Central Malabar Express, coach S6 is de-reserved from Thiruvananthapuram Central to Kottayam and in 16330 Mangalore Central-Thiruvananthapuram Malabar Express, coaches S5 and S6 are de-reserved between Kottayam and Thiruvananthapuram.
--------------------In train number 13352 Alappuzha-Dhanbad Express, coaches S2, S4, ST3, and ST5 are de-reserved from Alappuzha to Perambur. In 12624 Thiruvananthapuram-Chennai Central Mail, coaches S10 and S11 are de-reserved from Thiruvananthapuram Central to Ernakulam Town. In 16042 Alappuzha-Chennai Central Express, coach S7 is de-reserved from Alappuzha to Palakkad.
---------------In 17229 Thiruvananthapuram-Hyderabad Sabari Express, coaches S11, S12, and S13 are de-reserved from Thiruvananthapuram Central to Coimbatore Junction.
This is as per info in The Hindu,,