Originally Posted by
Wuxia
Will TK allow us to reschedule or cancel our tickets?
No.
Can OZ help us do the rescheduling even if the TK tickets are not purchased from them?
No.
It is OZ's responsibility to get you to IST as scheduled on the ticket they have sold you. If that flight is cancelled, OZ must rebook you on a suitable alternative flight, *A or not, direct or not, to get you to IST at a time that is convenient to you.
TK has no responsibility or obligation beyond operating the flights you have booked from them, and barring any further incidents, they will not waive any of their fare rules around changing the TK flights.
I'm not interested in your "don't buy nonrefundable tickets if you don't like this to happen".
Whether you're interested in this or not does not change the fact that these are the inherent risks of buying two separate tickets for one trip.