Late December is very much a peak period and the frequent flyer seats have been available for almost 8 months now – so it’s going to be very tricky for you to find frequent flyer availability. What you have going for you, though, is your willingness to be flexible with departure points and destinations, and also the fact that you have points in two programmes which will give you availability on different airlines – namely, Oneworld airlines (also Emirates and China Eastern) with your Qantas points, and Star Alliance airlines with your KrisFlyer points.
You have enough points to fly one way using your KrisFlyer points, or return using your Qantas points.
Now it’s just a case of sifting through airlines’ websites with a fine tooth comb until you find availability. It will be difficult given your timeframe. A few tips that might, just possibly, make things a bit easier for you:
In general, Adelaide is the Australian city with the most availability with outward flights.
There are plenty of airlines that fly directly into Amsterdam (including Emirates, Qatar, Singapore, Cathay etc) so start by looking for direct flights; otherwise, yes, the next best option is to look for availability to a nearby city. Try Paris, Edinburgh, Manchester, London, Frankfurt, Munich, Dusseldorf etc for starters.
I suspect that you’ll be looking for a needle in a haystack. You might get lucky and find suitable flights within a few minutes – but there’s an equal chance that it’ll take hours. Be prepared to be patient.
If all else fails, pay for a flight from Darwin to somewhere like Singapore and look for frequent flyer availability from there. As a rule, there’s greater availability from cities in Asia than from Australia.
Be prepared to think outside the square a little – eg. there might be availability on lesser-known airlines such as Asiana, EVA Air, etc. There’s no knowing where in that haystack the needle will be!
Hope this helps!