Thanks, found it and the following is CHANGE for YYZ-IST-TPE-IST-YYZ, all 4 segments in J with stopovers at IST in both directions. It makes sense that once you've flown the first segment, they'll have to reprice it at historical fares since it's technically impossible reprice a ticket retroactively (ie. wanting to buying a ticket with the first segment starting last week).

Unless one needs to change the date of the first segment it never makes sense to change the dates before departures, especially close to the departure dates. TK does warn you about NO SHOW, the only question is (I can ask TK offices later and update) up to how soon you can change the flights without No-SHOW, just hours before the flights?

ANY TIME CHARGE EUR 100.00 FOR REISSUE/REVALIDATION. NOTE - REPRICING CONDITIONS- -------------------- A-BEFORE DEPARTURE- ITINERARY MUST BE RE-PRICED USING CURRENT FARES IN EFFECT ON THE DATE THE TICKET IS REISSUED THE ITINERARY MUST MEET ALL RULE PROVISIONS OF THE NEWLY TICKETED FARE INCLUDING ADVANCE PURCHASE --AP MEANS- TKT MUST BE PURCHASED A MINIMUM NUMBER OF DAYS BEFORE THE FLIGHT DEPARTS - A CHANGE IS A DATE/FLIGHT/ROUTING/BOOKING CODE CHANGE. - CHARGE APPLIES PER TRANSACTION - PER PERSON FOR ADULT CHILD AND INFANT WITH SEAT. INFANTS WITHOUT A SEAT ARE NOT CHARGED THE FEE - NEW FARE MAY BE EQUAL OR HIGHER. WHEN THE NEW - ITINERARY RESULTS IN A HIGHER FARE THE DIFFERENCE WILL BE COLLECTED AND THE CHANGE FEE WILL BE APPLIED. - CHARGES SHALL NOT BE WAIVED FOR MEDICAL REASON - WHERE THIS FARE IS COMBINED WITH ANOTHER FARE AND ONLY ONE FARE COMPONENT IS CHANGED THE PENALTY CONDITIONS OF THE CHANGED FARE COMPONENT WILL APPLY WHEN MORE THAN ONE FARE COMPONENT IS BEING CHANGED THE HIGHEST PENALTY OF ALL CHANGED FARE COMPONENTS WILL APPLY - FOR DOMESTIC TURKEY SECTORS - WITHOUT CHARGE - - B-AFTER DEPARTURE- - THE ITINERARY MUST BE RE-PRICED USING HISTORICAL FARES IN EFFECT ON THE ORIGINAL TICKETING DATE. THE NEW ITINERARY MUST MEET ALL THE RULE PROVISIONS OF THE NEWLY TICKETED FARES SUCH THAT THE RECALCULATED FARE COULD HAVE BEEN USED FOR THE NEW ITINERARY IF PURCHASED ON THE ORIGINAL TICKET ISSUE DATE - A CHANGE IS A DATE/FLIGHT/ROUTING/BOOKING CODE CHANGE. - CHARGE APPLIES PER TRANSACTION - PER PERSON FOR ADULT CHILD AND INFANT WITH SEAT. INFANTS WITHOUT A SEAT ARE NOT CHARGED THE FEE - NEW FARE MAY BE EQUAL OR HIGHER. WHEN THE NEW - ITINERARY RESULTS IN A HIGHER FARE THE DIFFERENCE WILL BE COLLECTED AND THE CHANGE FEE WILL BE APPLIED. - WHERE THIS FARE IS COMBINED WITH ANOTHER FARE AND ONLY ONE FARE COMPONENT IS CHANGED THE PENALTY CONDITIONS OF THE CHANGED FARE COMPONENT WILL APPLY WHEN MORE THAN ONE FARE COMPONENT IS BEING CHANGED THE HIGHEST PENALTY OF ALL CHANGED FARE COMPONENTS WILL APPLY -- CHARGES SHALL NOT BE WAIVED FOR MEDICAL REASON - - FOR DOMESTIC TURKEY SECTORS - WITHOUT CHARGE - - NOTE- SEQUENTIAL USE OF FLIGHT COUPONS - THIS FARE IS ONLY VALID IF THE FLIGHTS ARE TAKEN IN THE BOOKED SEQUENCE. OTHERWISE THE FARE WILL BE RECALCULATED BASED ON THE ACTUAL FLIGHT ROUTING. -- ANY TIME- -- REVALIDATION/REBOOKING/REROUTING MUST BE FINALIZED BEFORE DEPARTURE OF THE ORIGINAL FLIGHT BEING CHANGED PROVIDED ALL CONDITIONS EXCEPT ADVANCE PURCHASE ARE COMPLIED WITH. CHARGE EUR 200.00 FOR NO-SHOW. NOTE - FLIGHT COUPON OF A PASSENGER HAVING A RESERVED SEAT BUT NOT SHOWING UP CHECK IN DESK FOR ON TIME IS ACCEPTED AS NO-SHOW RESERVATION NEEDS TO CANCELLED AND TICKET NEEDS TO REISSUED BEFORE THE ORIGINAL FLIGHT OTHERWISE IS ACCEPTED AS NO SHOW - CHARGES SHALL NOT BE WAIVED FOR MEDICAL REASON -