Chelsea Sherrard, 27, from Adelaide, SA, shares her true life story;
The car turned into my sister's drive and I barely waited for the engine to be switched off before jumping out. I burst into Sophie's house screaming with joy.
"Look! He did it," I said, proudly showing her the sparkling diamond cluster ring on my finger. "James proposed on the beach."
Sophie hugged me so tightly I could hardly breathe.
"Are you still keen…" I said, looking Sophie directly in her eyes.
"Of course I am," she said.
We looked behind us where James was standing with Sophie's fiancé, Jeff.
"And you guys are still okay with it, too?" I asked tentatively.
As if they had an option!
What we were referring to was a plan Sophie and I had hatched from the moment we'd met our respective boyfriends: we wanted to have a joint wedding.
Sophie and I were incredibly close. We always had been.
Growing up, Sophie was there for me, a protective big sister who always had my back.
Even when we left school we made sure we lived close by to each other. She was my closest confidante, my best friend.
I met James in a nightclub, several years before.
He had quickly become part of the family and he knew from the outset how important my sister was to me.
We were both thrilled when she met Jeff online.
"I think he's the one," she told me after their first date.
And from that moment on, Sophie and I had been plotting and scheming to get married together.
Sophie got engaged first when Jeff proposed over a romantic meal.
It felt like forever before James popped the question but it was actually only a year later.
Now we could officially start planning our double wedding.
Luckily, James and Jeff already got on like a house on fire.
They knew how close Sophie and I were so they good naturedly agreed to let us tie the knot in the same celebration.
Sophie, Mum and I started planning in earnest.
The first thing we did was to book the venue, Adelaide's Glenelg Golf Club.
Then we drew up our guest list. That was a doddle.
Clearly, we had the same relatives, but we also had always been so close that we had all the same friends.
The next thing we needed to do was find matching wedding dresses.
I'm a size 10, so a different shape to voluptuous Sophie who is a size 24.
Sophie, Mum and I went to several shops and we tried on loads of different dresses.
And then eventually I put on a beautiful one made of ivory taffeta fabric.
As I came out of the dressing room, Sophie burst into tears.
"You look beautiful," she stammered. "Seeing you in that dress, it's made it all seem so real."
She tried it on in her size and I welled up too.
"Yup, this is definitely the one," I said, hugging her.
It was such an emotional moment.
Before the wedding, we had the hens' party and yet another excuse for a fabulous joint bash.
Together with 25 friends, two weeks before our big day, we tucked into pizzas at our favourite restaurant, before dancing all evening at a night club.
"I love you so much," I declared drunkenly on the dance floor to my big sis.
"There's no-one I'd rather be getting married with," she said.
Not only were we getting married together, we were also being each other's maid of honour!
Both our husbands-to-be were quite shy, unlike us, so they were more than happy to share the spotlight.
Sharing the $35,000 cost of our wedding was a total bonus, too.
After all our planning and preparing, the big day finally arrived.
Sophie and I giggled excitedly as we sipped champagne while we had our hair and make-up done at the same time.
Then Mum helped us into our matching wedding gowns and took us to meet our dad.
The Rosemary Clooney song Sisters started blaring out of the loud speakers and Dad hooked each of us into his arms.
"Ready girls?" he asked proudly.
"Yes," we said in unison.
Sisters, sisters, there were never such devoted sisters… went the song as we walked down the aisle.
When we reached the altar, we each took our grooms' arms and stood side-by-side.
We read our vows individually.
"I now pronounce both couples, husband and wife," the pastor said.
We'd planned this before, of course, wanting to start our married lives simultaneously. You could have synchronised the moment with a stopwatch, as Sophie and I kissed our husbands.
I'd shared everything with my sister, throughout my life, so sharing this special day was simply perfect.
Our only real point of difference came at the reception.
James and I had chosen a sweet cake, while Sophie and Jeff had opted for a savoury cheese gateau.
"Today has been absolutely perfect," I said, cuddling up to James in bed that night.
"Thank you so much for agreeing to a double wedding."
"I wouldn't have had it any other way," he said, kissing me.
The next day, we joined Sophie and Jeff again, this time at the airport, ready to jet off for a once-in-a-lifetime two-week honeymoon break in Thailand and Singapore.
Our new husbands had drawn the line at staying together, so we stayed in separate villas.
But it meant we were able to meet up at the pool and the bar and enjoy our honeymoon as a foursome, while having our own space.
It worked out perfectly.
Sophie and I wanted to spend all our time lying on the beaches gossiping, while James and Jeff went exploring.
We're all back home now and I just feel so happy I got to share my hens' night, wedding day and honeymoon with my sister and best friend.
Now let's see if we can plan our babies as perfectly…!
"I was happy to sit back and let the girls and their mum plan the big day.
When I first saw Chelsea and Sophie together, I knew they were close, so I was more than happy to go along with the double wedding plans."
JAMES ADDED: "The wedding really made us so much closer as a family."