Wow, that's a poor time even for people in Australia to attend a wedding, with family vacations, higher hotel costs, etc.

Your personal cash budget's ability to augment redemptions is the only other thing I can think of to play with. What about terminating somewhere relative nearby in SE Asia/SW Pacific - if there is a reasonably priced revenue flight to MEL? Even that won't be truly cheap given the season even with LCCs.

Or if you just flat-out can't make it work, then hopefully she will understand. It's not worth blowing your finances and/or mileage balances.