Originally Posted by
PVDtoDEL
TK will cancel and refund the IST-BLQ segment if OP misconnects (and requests it), and it would likely be cheaper to buy a new ticket ex-IST than it would be ex-Italy.
Cancelling 1 segment upon request is permitted but will be subject to re-pricing of the ticket to YYZ-IST, and BLQ-YYZ, which will be more expensive than the J sales TK has been running out of YYZ to select European cities.
Again, anything is possible with TK just like Turkey, what I've just stated are official verbiage.