Going all the way to Oz with a partner isn't going to work as that will be 200-300k each.
If you can get to SIN on your voucher and then onwards on a partner it would be 140k + 4x40k = 300k. Similar via HKG/BKK would be 320k.
If you can get to Oz this is a bit of a tangent but on the SQ Krisflyer chart South West Pacific is one big region including OZ, NZ and the Cook Islands and round-trip business on NZ is 35k pp. If you haven't already exhausted this option you can pick up 70k Krisflyer miles very quickly from an Amex chargecard each (one gets a free Gold, refers the other for a £450 Platinum).