I take it people have travelled on these European / Brazilian tickets?
Just showed an example of these tickets to Dad (BNE-SYD-MNL). Absolute bargain (about $100-$200 less than the normal price here), but apart from Dad not liking going through SYD (he's had less than great experiences at SYD Customs; no he has no "record"), he's scared that it's so cheap (no YQ) that he may be refused passage because he "hasn't paid the right fare" or something like that. Basically he's scared the fares or the use of the fares aren't legit.
Someone want to share some experience? Qantas legally can't demand more payment at the airport, or invalidate the tickets, can't they?
Love the tip, though. Might try it myself...