First can I check that I'm understanding you properly. What you're wanting to do is:

• Travel from Australia to Europe in December 2026
• Return to Australia
• Travel from Australia to South Africa in September 2027
• Return to Australia

You thought of doing straight forward return tickets (Australia-Europe return, and a later Australia-South Africa return)
And you are exploring whether a RTW will give you more/be better value for you.
At this stage you are not looking to travel more widely - say in North America or Asia.
But would be interested in South Pacific travel, while you are back in Australia.

Have I got it right?

To achieve what you want, you must start from somewhere in Tariff Conference 2 (TC2 - i.e. Europe/Middle East/Africa)
(see Note 1 below for why starting elsewhere will not work for you. And by the way, if you are new to RTW planning I recommend you read the wiki in The Oneworld Explorer User Guide)

With your proposed itinerary (mapped by Mwenenzi), you will use other means get yourself from MEL to OSL to start the RTW and then return from OSL to MEL at the end. This eastbound itinerary has 5 continents (by flying Europe/Middle East to South West Pacific you automatically include Asia).

If instead you fly westbound you can avoid Asia, reducing the itinerary to 4 continents (a saving of ~NOK8000 in the business class base fare). Here's a very simple westbound itinerary OSL-LHR-LAX-SYD-JNB-LHR-OSL

Another option is to start from elsewhere in TC2. How about South Africa? It is one of the lower cost starting countries too.
A minimalist itinerary for this is JNB-LHR-SCL-SYD-JNB. By starting in Africa, there will be no restriction on stopovers in Europe/Middle East (it is no longer your continent of origin)

If you start in Europe then you get to visit Europe twice.
If you start in Africa then you get to visit Africa twice.

Note 1
One of the Fare Rules states: 4(b) "Travel must be in a continuous forward direction between TC1 - TC2 - TC3..."
So you start one TC, then visit the other two and end back in your starting TC.
Therefore, if you want to visit a TC twice then it must be the starting TC.
You are wanting to visit TC2 twice (Europe to start, and later South Africa).
Therefore you must start somewhere in TC2.

Thank you so much. Yes, we are heading to Europe in December and then South Africa the year after. Coming home to Australia in btw. Being based in Melbourne we would take advantage of the SWP extra sectors to go somewhere we havent been before (like Tonga). We have looked at return flights to each and seeing what is best value out there.
We are looking at Business Class and so DONE4 or DONE5. We've done a couple of these tickets starting in Sth Africa, or Tokyo on prior trips.
The challenge with the Westbound trip is time. (Which in December is unfortunately in short demand ).
Do you think we are best to start OSL-PER via DOH or via LHR (both transit only) based on first carrier and taxes?
thanks again

So already have separate tickets to EU?
On you previous *ONE* trips did you book on line or with a travel agent?
Note real taxes and carrier surcharges YQ YR are not the same thing. Is a post by serfty on minimizing surcharges. With so many QF flights will have a lot of Qantas carrier surcharges.

There are several factors I'm aware of:

• YQ/YR "fuel surcharges" are assigned by airlines to sectors. E.g., booking AA vs BA vs AY transatlantic may have different YQ/YR for that sector. The amount each airline charges for each flight is in the GDS, which the ticketing airline or TA uses to calculate the total price, but I'm not aware of any tool that makes it easy to extract the data. The closest might be to use matrix.itasoftware.com to price a simple one-flight one-way and see what it shows for the YQ/YR.
• Some airlines are careful to charge every YQ/YR applicable (hello, AA) while others (hi, JAL) sometimes omit a YQ/YR here and there.
• Some airports or countries have higher taxes (actual taxes, not pretend taxes that are really carrier-imposed charges). For example, a flight or series of connecting flights that originates in the U.K. incurs the U.K. APD (Air Passenger Duty), a tax based on the distance from London to the capital of the terminating country and if the class of service is coach or a higher cabin. If transiting London, it's best to make sure London is a connection rather than a stop, or if it must be a stop, that the flight(s) from London to the next stop are to a nearby country,

If its an actual tax imposed by a country that applies to all airlines, then it isn't YQ/YR, it would have a different code. YQ/YR are airline-imposed surcharges (what some refer to as "additional overcharges" or "carrier overcharges").

Your TA should be able to give you a breakdown of the taxes, fees, and surcharges, but the ease of obtaining this varies by airline/TA. For example, I recently purchased a BA-issued ticket, and asked BA agents for the info. They insist that it's impossible to know until after I fly, at which point I can use a form on BA's website that discloses all fees and taxes. BA's eticket receipt that is emailed upon purchase does show the base fare, actual taxes, and airline-imposed fees, but as a whole, not broken down by outbound versus inbound, much less segment by segment. When purchasing a ticket from AA, the emailed eticket confirmation lumps carrier overcharges in with taxes, but one can call AA and the agent can provide the total YQ/YR. I called JAL to get the breakdown for a recent DONE5 that I purchased from them, and to my surprise, the agent started rattling off each charge by its code and its segment number! For example, "Segment six, YQ $125." When calculating what AA earnings should be, knowing the specific segments is tremendously helpful.

Yes have a one way ticket to EU to start us off. I will check out posts re taxes... thank you. Now to till in sectors with some fun stopoffs along the way!
thanks again for your help

This helps alot thank you. So with Asia and USA and SWP and EU and Africa thats our 5 continent... time to find some fun stopovers in USA and Asia then. Thank you again!

Just on this one small point, I recommend transiting DOH rather than LHR to get between Europe and Australia. QR operates their Qsuite-equipped 777 and A350 between DOH and Australia. QR's A380s do not have Qsuite. Qsuite is the nicest business class in oneworld. It's even nicer if you're flyig with someone because you can get an EF seat pair, which open into essentially your own two-person suite.

Indeed, type of fare limitation is frustrating. I've run into it before on an AONE5, and am now being forced into alternate flights while waiting for 'D' to become available on a JL flight for a DONE5 I've purchased. EF shows D8 but inside a DONEx it's D0.

Thank you very much for this reply - super helpful. I'll see what else I can get for now, but also try asking after the fact. As I think my next trip will be booked with JL, then I should have that option also.

After my recent JAL DFW-HND in J on their A359-1000 I would say QR have serious competition. (I also flew QSuites DOH-JFK on the same DONE4.)

Having posted that, I'll happily fly either ...

I flew JL's A350 in F some time back, and as I was first on board I took the opportunity to check out their J seats. A massive improvement over their old J product, to be sure, and like QR's Qsuite, with walls and a door high enough to actually enhance privacy (unlike the laughable walls and door on BA and AA's new J). However, the J seat has almost no storage (just a shallow cubby on top of the side area, unless I missed something). There is a clothes closet that slides out, and a shoe drawer. Qsuite has ample storage. If JL added some compartments to store stuff, they'd have an amazing product.

QR charges a "whole itinerary" YQ, and I think so does QF, so these cannot be picked up even if you try to price individual sectors.

Don't forget to try codeshares. UL has greatly limited availability in the D fare bucket, but I was able to get the flights I wanted from the AA RTW desk last night using one QF codeshare and one JL codeshare on flights operated by UL that had zero UL D availability. Got the codeshare info from EF.

I share your sentiment based on my recent HND-JFK on JL (D fare) as my first segment of a DONE3. Window seat has so much storage areas!

That's great! I stopped purchasing RTWs from AA a few years back, when AA instituted a rule that all flights booked must be either prime or an AA code. Glad to hear they either reversed that, or perhaps you got lucky with an agent who didn't enforce it.

I had an RTW booked via JL a few years ago where I used an SWU to upgrade an AA prime flight. When AA reissued it, they changed all codeshares to prime. Really pissed me off because it slashed the earnings.