3.3.6 In the event you do not show up for any flight, for which you are holding a reservation, without advising us in advance, we may cancel your return or onward reservations as shown in your Ticket. However, if you do advise us in advance, we will not cancel your subsequent flight reservations.
http://www.airchina.com/mm/en/genera...rnation3.shtml

The above condition seemst to show it maybe possible.