Laker, have done exactly that several times this year.
I do not refuse discretion. On a day flight, if we are all rested then discretion is a possibility. But on a night flight, I will never use it unless caught in a hold on the return.
Often on these night turns they try to hold the aircraft for pax or bags (or slots).
My call to VPNC is simple. I will do anything I can to operate the flights but discretion is NOT an option.
So VPNC can 1) call in a new crew and wait for the pax etc 2) leaves the pax/bags and we go on time or 3) we can wait and still fly the outbound trip but the airplane will be stuck at the outstation.
VPNC will often say "OK, go and we will try to get them to turn you quickly". My response is always the same - Firstly the block times are often only 5 min longer than the flight times (ridiculous) so they will not be able to speed the turn. BUT--this is YOUR call VPNC! When the aircraft is grounded in India with 300 plus hotel rooms it was YOUR decision! I have given you several options, if you have another idea then throw it out, I am willing to work with you. What I am NOT willing to do is to go into discretion.
They have always decided to leave the bags etc behind!
I don't refuse discretion to be difficult. I refuse because with 90 plus hours per month I know how tired I am am at night and pushing that even further is unsafe.