QF / JQ transfer baggage question

[rocket]

Hi,
Have searched but can't seem to find an answer, so apologies if I've missed it somewhere ...
Travelling MEL-SYD on QF, then SYD-DPS on JQ, both in business, on separate tickets / itineraries. Then same in reverse.
Can I check baggage through to DPS in MEL and use air-side transfer in SYD, or do I have to collect in SYD, get train with baggage and recheck in int terminal.
All I can see so far is that I can through-check if both flights are on one itinerary.
Thanks in advance.

 

[wandersen]

Just last week I tried to do this from Syd-Mel-Christchurch (Mel to Christchurch on jetstar) And was told flat out no it can't be done at the premium service desk in Sydney.