In Reply to: Jetstar upgrade... quick question posted by Rockin Robyn on Monday, 11. February 2013 at 08:36 Bali Time:
You only get the 30kg for the BC leg. You are not entitled to that allowance if your domestic flight is economy.
You need to ring Jetstar and ask them , get it in writing if they say you can have the 30kg on the economy leg.
No point getting lots of conflicting advice here. :)