Off loading baggage in DXB on a return of a RT ticket...
 

X-DXB-SYD is a possible ticket. Round trip.

On the return, how can a pax stop in DXB and collect their baggage and not continue to DXB-X and (later) make their own way on a totally different ticket DXB-X. :confused:

Changing the ticket (X-DXB-SYD, rt) will cost MORE than the DXB-X one-way. :rolleyes:

build in a stopover or long transit in dubai and ask check-in at SYD to short-check the bag. stopovers are generally free, so you can stop a week in DXB before onward to X, simply don't board the onward flight to X.

My impression is the OP has already booked the ticket?

I dont think there is much you can do. I'm not sure they'll just tag your bags to DXB tbh. They know the tricks!

Could be savings to be had in eating the change fee though rather than have a fare recalculation to terminate in DXB!

Yup, may be able to pay the change fee, with no fare difference if lucky, or even a lower fare resulting in reduced change fee or even discount.

Lastly OP may already have a long layover if ticket already booked. I'm not sure though, wording leans toward not yet booked in my opinion: "is a possible ticket"

Yes, not yet booked the ticket. The long layover (in DXB on the return trip) sounds like a nice way to do things satisfactorily - that is assuming the baggage can be checked to DXB (with the implication that it will later be checked on to DOH - NOT).

It can. Just tell the agent you're heading into the city and need an item from your checked baggage. If layover exceeds 24hrs you have to collect in DXB.