G'day Marcus,

The 4x4 Equip swag is 150cm wide, and the Mudge C5 Double sleeping bag is also 150cm wide.
You'll have no issues using them together.

G'day Lyndsey,

Yep, they sure can.  The Mudge is opened up like a blanket with two sleeping bags joined like a sandwich.
As a result, there will be a zip slider on both sides of the 'bag'.

G'day Mitch,

Coleman have a red guard on all their zippers, which they call a "ZipPlow".
Generally this makes for snag-free opening and closing, but it also acts as a stopper to prevent the zip from sliding open without intention, so your bag will stay closed and warm all night!

G'day Fiona,

Fellow whippet owner here, so I hear you, they do feel the cold don't they. The Mudgee C5 double should suit both of you, however they don't have a fleece liner, so that may or may not be a deal-breaker. They are machine washable though, which is handy post trip. Another good option to consider is the Pilbara C0 sleeping bag, you could get one each maybe? I tend to just bundle mine up in their jackets, and take their fleece beds and if they're too cold they'll find a way to snuggle under the end of the sleeping bag.

G'day Sue,

Yes, the Mudgee C5 Double Sleeping Bag is machine washable on the gentle cycle. It should fit in most domestic machines.

G'day Rob,

The Coleman Mudgee C5 Double Sleeping bag is a great option for a summer-weight bag/s.  There's no problem with your kids using these and as the child-specific bags are aimed for toddlers/younger children, the Mudge C5 would be a batter long term investment.

G'day Jake,

This would be a great bag, yep!  You can select a temperature comfort range in the left-hand menu when looking at sleeping bags, that will give you an idea of what other options there are.  Having said that though, I think this is one of the better options. Given its square shape, it allows you to open it up to a lovely blanket if needed, also with that brushed fabric on the bag itself, its alot nice against the body in warmer weather that some of the shiney fabric.