I was in Melbourne too and we used all cotton stretchy wraps for swaddling then cotton weave blankets layered on top and on really cold nights more flannel wraps too. We kept an eye on how warn they were and definitely wasn't overheating even with a little heater on 16 overnight... Brrrrr it's cold hey! Once old enough we used sleeveless 2.5 tog bags with blankets on top but by then they would roll blankets off so we would layer up underneath.