Availability on the Kangaroo route is always tight in July/August. As you noted, it is the peak travel preiod on that route. Hence most of the FF award seats are reserved 355 days previous. Some poeple are good planners and know they want to travel 12 months before hand, and they jump on all the available seats.

Yes, Qantas, BA and CX do release more seats occasionally. In my experience, Qantas does not do this until very close to travel date, say in the week or two prior. And that does not help for planning return trips.

Availability for FF awards in economy for Gold and Platinum FF mmebers is better as they take those seats from a different fare bucket (T class vs X class). But that does not help unless there is a Gold of Platinum FF member in the family and you can take advantage of the new Family Transfer facility to get the points to the person who has access to the enhanced availability.

Also make sure they check options such as Cathay Pacific and even routing via South Africa.