If you have a look at Flight Aware, you will see that these days, Jetstar flies JQ35/JQ37 direct from MEL and SYD respectively to DPS, the 2 cities, ie, MEL and SYD don't connect in reaspect to these 2 flights anymore.
I have taken the JQ 787 and the JQ330 (as a D stickered dom pax) from SYDint to MELint about year and a bit ago.
These days, its rare, maybe only when JQ really wants to.
You could go SYD - AKL in whY/flexY on LAN with a QF flight number, and then AKL - MEL on EK with a QF flight number.
A lot pricier than that elusive JQ dom pax on an int flight thingo. Plus more QF SC.
The last time I saw it was Mar this year.