I agree with above posters re: Perth being the only valid Asia routing using SQ so far as YYZ and YEG are concerned. I would assume that leaving from Fredericton you would get some more miles in the MPM and depending on your actual routing you may be able to make it work. Find out what the MPM is ex-Fredericton and then play with routings/mileage.

IIRC SQ and NZ are 350 days out for booking while AC is 355 days but stand to be corrected. Any use of UA will knock you to 331 days. Also, you will need to call and pay a fee. I would HIGHLY recommend you make a booking for the outbound with a dummy return a couple days later. Once your actual return is in the window call back and change the dates. If your trip is not long they may not ticket the itin before you call back in which case you get the change for free. If it does ticket then there is a fee of some $50 or so. Well worth it.

Fully agree with getting a good agent. Any resistance or confusion; drop the call and try again. YVR AP agents are the best IMHO ^ I had one put an itin on hold for a few days until she returned from Whistler as we had the whole thing figured out but had miscalculated the last flight on the return by a day meaning it was outside the window - talk about pro-active service

Good luck! PS - Given SQ ex-YVR has no F and NZ does not either I am not sure it is worth the extra pts for the NA-SIN in F ex-LAX or SFO. This LAX/SFO routing may also increase your mileage.