emcampbe

No. The value of each ticket remains in each individual PNR, and can not be combined. While the word canceled is used - you are only canceling the segments - the PNR remains active and you are simply changing to a new date/route to be determined later. Assuming these are typical non-refundable tickets, and you canceled prior to departure of the first segment, you are able, after paying the change fee (if applicable) in new $, and gain access to the value in the PNR.

The value in multiple PNRs can't be combined, however, if you want, you can book one way instead of round trip to use 2 of the older ones for one round trip. Sometimes, however, 2x one way is more than a round trip, and also note if you need to make any changes down the line, it will cost two change fees if you need to make changes in both directions.

Also - I notice you used the word "years" I'm not clear if you meant years as in the cancelations were made over the last several years, or referring to the whole year of travel (I.e this year only). You must rebook within one year of the original issue date of your ticket. If you don't, the value goes poof. Just something to think about. So for example, if you booked a ticket on Feb. 2, 2014, and then canceled it later, regardless of your start date of travel, you must rebook a new itinerary by Feb. 1, 2015.