I have to be very frank with you. Your best chance is to buy revenue ticket. There are several factors in your situation making award booking virtually impossible:
1. Only 4 months out:
This is the worst timing in trying to find award seats. By this time, most award seat would have already been taken as people would have already planned their vacation.
Even if there are a lot of unsold seats, as there are still 4 months to go, airlines will try to sell these seats.
- Peak season:
- I assume you are going on the school holidays with kids. But remember, July is not just Australian school holiday, it is summer break for Asia and US as well. So you are competing with all over the world.
- 4 passengers:
Even 12 months out, it will require a bit of luck to score 4 seats on a very generous airline during low season. Most airlines would just release 2 seats each for first and business class.
MH is the most generous airlines in releasing award seats, so it was your best chance. the problem is, since the devaluation, it is getting very expensive, higher than SQ as you said.
Upgrade is not a good idea, not only you have to buy the most expensive flexi economy ticket (which usually cost > 2x of the sale price), upgrades usually comes from the award inventory. If all awards are taken, they won’t upgrade you. Airlines won’t open up award inventory just for you. However, they might open up more spaces as time comes (usually about 1-2 weeks out) if there are a lot of unsold seats. However, being a group of 4, that again reduces your chance, as you will need to be in a flight where there are more than 4 empty seats and no one else is competing with you for those seats, or your status is much higher than them.
There are certain airlines (eg. CX) that will only upgrade you to the next class up. So if the flight comes with premium economy, you can only get upgraded to it from economy, not to business.
If experts like Award Pro can’t find anything for you, I really have to say you are out of luck. Of course, if you have millions of Membership Reward points, you can always redeem SQ on their standard/Full (fool) award.