To have no clue about how to book an "Open Jaw" flight to Oz!

[carbriana]

We want to book return flights to Sydney via Singapore, that will also allow us to break the journey and stay in Singapore for a few days on the outward leg of the journey. I'm pretty sure this isn't an unusual thing to do, and I've picked up that it's called an "Open Jaw" flight (yes?). But we've visited the websites of several major airlines (BA, Qantas, Singapore Airlines) and a couple of flight comparison sights and can't see any way to search for it. They all just seem to advertise standard return flights. DH says we will need to go to a travel agent, but I'm not giving up yet ... what am I missing?

You need to click for "Multi City" which will open up more than 2 legs and you can enter as follows as an example:

LHR - SYD. 10 Nov 2019
SYD - SIN. 20 Nov 2019
SIN - LHR 24 Nov 2019

Very easy to do on Skyscanner If that proves easier.

Hope that helps! (Retired travel agent)

Chose the multi flight tab.

Then put in flights, say:
Outbound
London - Singapore Tuesday blah blah blah
Singapore- Sydney Friday blah blah blah

Have lovely holiday

Return
Sydney - Singapore Tuesday blah blah blah
Singapore - London Friday blah blah blah

It shouldn’t make a difference to the price compared to a return on Singapore Airlines etc 🇸🇬
They’re called stop overs:
Singapore Airlines website...
‘Stay for minimum 2 nights and you can choose free admission to Universal Studios with our Singapore Stopover Holiday Plus programme. ‘

Yes it’s multi city, not open jaw. Open jaw is flying out of a different city to the one you flew into. If you’re so unsure, and it’s an expensive flight, perhaps visiting an agent is the way to go. They can also organise your travel into Singapore City for you.

(Also retired from travel, specialised in flights).

As previous posters said, you need a multi city / stopover option for your trip. For future reference, an open jaw flight is where your outbound arrival and return departure points are different e.g. on the way out if you flew London-Sydney, did some travelling around Australia and then on the way back did Perth-London.

“Singapore Airlines

If you’re flying through Singapore on Singapore Airlines, you should most definitely check out the airline’s clever stopover holiday package. Starting from S$45, you can get incredible value from these stopover offers, which include a nights hotel stay, complimentary SIA hop-on bus rides and access to many of the wonderful attractions Singapore has to offer.

Next time you’re on a long flight around the world, think about breaking things up and adding a fun extra stop to your itinerary. Here’s a few tips for your time in Singapore too, including the must see new Jewel waterfall and mall at the airport.“

Cathay, Finnair & Icelandair offer particularly good stopover offers in Helsinki and Reykjavík for future trips.

I did exactly what you're suggesting a few years ago and priced it up online using multi city option on sites like last minute, opodo and sky scanner but I also called a few people like dial a flight and trail finders and trail finders where the cheapest at just over 1k so I'd also reccomended giving them a call.

Yes to the multi city.
Consider making it open jaw too - we flew into Sydney, had a fantastic holiday, and flew out of Melbourne (having used cheaper airlines for several internal flights).