As our friends and professional wedding planners, Mike and Katherine hadn’t missed a detail. From the outside, the village hall looked ordinary. It was booked for our exclusive use because no-one else needed it on a quiet Tuesday afternoon. Inside, however, they’d transformed it into a chapel. There were flowers, ribbons and candles laid out everywhere.

My bridesmaids all wore matching sage green dresses as we walked down the aisle: Tiff on the left, Samantha on the right, and Fiona lifting the train of my dress to make sure I didn’t trip up. Katherine acted as DJ. In place of the traditional wedding march, we’d selected Somewhere Only We Know.

When we reached the front of the hall, the ladies lifted my veil before stepping behind me. I looked around at the select crowd of seated guests. Jack, Thomas and Steven were all wearing identical navy suits in the front row. Sitting by herself in a white dress with black polka dots, Rachel was one of just two family members present.

And straight ahead, donning the traditional black suit, my groom: Ryan.

Was this sibling marriage all above board? Absolutely not. But did it feel like the real thing? One hundred percent.

After the wedding of Tiff and Samantha exactly a year before, Jack joked how Ryan and I would be next. Rather than fizzling out, however, that throwaway remark gained arms and legs as everyone pitched in more detail and ludicrous suggestions. Mike and Katherine stepped up and said they could help make it happen.

This wedding was supposed to be based on a non-religious ceremony, albeit playing fast and loose with some of the wording and conventions. Mike had nonetheless hired a vicar costume.

‘We are gathered here today to witness the marriage of Ryan and Rebecca,' he intoned. 'Should anyone present know of any reason this couple should not be joined in marriage, speak now or forever hold your peace.'

'I'm sure we can all think of a good reason,' said Jack, almost predictably.

After a general groan, he continued. 'Ryan Cronan Milk, will you take Rebecca to be your wife? Will you love her, comfort her, honour and protect her, masturbate with her, and be equally faithful to her as you are with any other partners, now and in the future, as long as you both shall live?'

‘I will.’

‘Rebecca Rhea Milk, will you take Ryan to be your husband? Will you love him, comfort him, honour and protect him, masturbate with him, and be equally faithful to him as you are with any other partners, now and in the future, as long as you both shall live?'

I looked at my other partners Thomas and Steven before I answered. They initially felt left out when they realised we were serious about this ceremony. We helped them to feel included by offering them joint best man duties. Jack then went into a sulk, so we gave him the job of organising the stag night, albeit reluctantly.

They were all smiling as I answered, ‘I will.’

‘Excellent,’ said the Reverend Mike, ‘and now for the vows.’

That was the cue for the boys to stand up. Thomas handed Ryan a card and a ring. Both of us had agreed from the outset we would rather show our love than talk about it, so we kept our vows to an absolute minimum.

'I take thee, Rebecca,’ he read from the card, ‘as my sister second and my lawful wedded wife first.' That reflected the order in which we considered ourselves. We wanted to be seen as any other couple, not as siblings. He slipped the ring onto my finger, and I found myself incredibly turned on by the sense of ceremony and finality.

Steven handed me a card and a ring. ‘I take thee, Ryan, as my brother second and lawful wedded husband first.’ I slipped the ring onto his finger.

'And finally,' said our officiant, 'you may kiss your sibling and your spouse.'

We kissed deeply as Katherine played We Are Family. I was about to leave the hall when I was reminded about signing the register. Throughout the process, Mike and Katherine had given us replica paperwork to fill in, adding to the feeling of authenticity. They even obtained the list of intended marriages in the parish that week and edited our names into it.

With the papers signed, we stepped outside the village hall. Our friends were ahead of us and they threw confetti right on cue as we kissed again.

Mike and Katherine specialised in planning weddings for couples whose families disapproved in some way. As first cousins who were legally married, they had a heap of personal experience, reflected in the name of their company: Chaos to Kinship. Two vehicles were parked outside. Katherine would be driving us in an old-fashioned black cab with tins tied to the back bumper. Mike would follow in the minibus with the rest of the guests.

We were going home for the reception, which jointly acted as a housewarming for our relatively new place. The cousins would then return to the hall to clear up, then join us later for – of course – copious masturbation and sex.

As the cab drove off, the metallic rattling followed.

‘Could we not stop and take them off? asked Ryan. ‘That’s doing my head in.’

Katherine looked in the rear-view mirror. ‘You won’t have to stand it for long. Would now be a good time to mention you’re not going home?’

‘Why not?’

‘The rest of us have booked you a place in the village. It’s yours until this time tomorrow.’

‘What?’ I asked. ‘How much is that costing?’

‘It’s covered,’ she said.

‘You’ve gone to so much expense. We only paid you cost price.’

‘We all chipped in for it. Jack offered us the gym again, but what a horrible place. I don’t mean to be funny, but is he now a personal trainer there? I never know whether to believe him.’

‘He’s a PT,’ said Ryan. ‘He’s not lying about that, for once.’

I was preoccupied. ‘Where is this place?’

Katherine pointed ahead and slightly to the left. ‘Just there.’ The cab turned up a dirt track, passing a sign pointing to The Old Stables. As we approached, I could make out a wide stone building with an entrance hall in the middle joining its two wings.

‘And that’s all ours?’ asked Ryan.

‘For the next twenty-four hours.’

On arrival, our planners unpacked the catering from the minibus with ruthless efficiency. The rest of our guests had also secretly brought their overnight bags.

‘Um, me and the wife.’ The phrasing took me by surprise, and I rather liked it. 'We didn’t know, so we haven’t brought anything.’

As if waiting for his cue, Mike pulled out two red suitcases and checked the tags. ‘One for him, one for her. We’ve packed everything you need in these.’

‘They’ll do for your honeymoon as well,’ added Katherine.

Ryan and I hadn’t actually booked it yet. Gibraltar was the top of our list. It would be sunny, everyone would speak English, and we could simply be like any other couple for a week.

Mike set up the catering on some tables in the spacious entrance hall. Katherine, meanwhile, showed us around one of the wings.

‘This place is normally hired out to highschoolers and the like. Because we’re a smaller group, the owners have only unlocked parts of it.’ She led us down an adjoining corridor and opened the first door to the right. ‘This is the staffroom. It has a lot of cushioned seating you can use for masturbating. Just pull down the blinds for privacy because there’s a public path behind.’ She then led us back into the corridor.

Samantha looked at the ceiling. ‘I wonder how much this place is worth?’

‘More money than I have,’ I told her. ‘The mortgage is a lot, even between three. Still cheaper than renting, though.’

‘Do your mum and dad not think it’s odd? You sharing a house with your brother and Fiona?’

‘No, they think it’s just a sensible way to save money, little do they know.’

‘And I don’t get along with my parents,’ added Fiona, ‘so I don’t care what they think.’

‘You’ll still need a housewarming,’ said Katherine, opening a door further down the corridor. ‘Anyway, this is the only unlocked dorm. Twelve beds in six bunks. Unfortunately, all single, but I’m sure you can improvise. Again, pull down the blinds for privacy.’

Rachel inspected the basic but solid beds. ‘Where was all this at our Scout camps?’ She chiefly addressed Ryan and me, who had all been members when we were young. ‘We had mattresses on the floor.’

When our sister had been introduced to the group, she and Jack immediately bonded over acerbic humour. Before either of us could agree, he chimed in. ‘You’re a lot older than us. Did they let girls in the Scouts back then?’

‘Yes, and we ate little gay boys like you for breakfast.’

‘And finally,’ said Katherine, ‘you’ll need the bathrooms, which have showers in them. I suggest we all use the Ladies, which are right next door here. If you really want the Gents, go back through the entrance hall and into the other wing. Any questions?’

‘I have one,’ I addressed the boys. ‘What happened on the stag night?’

My latest attempt to catch them off-guard had failed. Not one of them had breathed a word about it. We heard the stock answer again: ‘What happens on the stag stays on the stag.’ Our leading theory, albeit with no evidence, is that they had a few beers and encouraged my brother to do something gay with them.

‘Come on,’ said Samantha. ‘We told you what we did. A-B-C: archery, bookbinding, clit-rubbing.’

‘I have a better question,’ said Jack, ‘when can we start the wanking? I’m packing a cucumber down there.’ He squeezed his erection through his trousers.

‘I didn’t know it was green,’ muttered Rachel.

‘So am I,’ said Tiff, easily squeezing her sizeable clit through her dress.

‘Whenever you want. Like I say, Mike and I are going back to clear up the hall, but you can all get started.’

‘Executive bridal decision,’ I raised my hand. ‘We don’t start anything until they’re back.’

‘We could at least do the Yes-No Thingy,’ said Jack. With those words, Rachel and I looked at each other. I knew we were putting off the inevitable, but every extra minute of delay felt like a small win. ‘It’ll still be a surprise when they get back.’

‘That’s not the plan,’ I declared, probably with a snappy tone. ‘Everyone’s going to be there for that. Unpack your cases and take your minds off your genitals.’

I flashed a special sibling stare at Rachel, although Ryan picked up on it. We huddled together, and he asked discreetly, ‘Do you want me…?’

‘No,’ we both whispered.

‘We’ll shout if we need you,’ I added. Ryan nodded and stepped back. I whispered to Rachel. ‘Where’s that other bathroom?’

As we went to find it, she grabbed a bottle of wine off the catering table. She’d developed a drinking problem over the last few years and had, naturally, started at breakfast that day. It wasn’t the time to give her another lecture, though, as there were bigger discussions to be held.

When the topic of marriage had first arisen, my brother asked for a special wedding gift that Rachel and I had the power to grant or to deny. We’d debated the matter ever since it arose, both with and without him, because it carried great emotional weight and the potential to alter our family dynamics permanently.

The gift in question was a once-in-a-lifetime threesome where both his sisters interacted with him and with each other.

Rachel and Ryan had been intimate before, which once ended up with penetrative sex. I know because I watched it. She wanted to find out what I saw in him, and I unsuccessfully tried to delay it until she was sober. I spoke to them individually afterwards. It seems they both found the experience not entirely unpleasant.

Once we found the bathroom, I perched on a sink while she sat on a toilet, fully clothed with the cubicle door open. Unsurprisingly, the place had that undefinable stink of boys but the windows wouldn’t open. We each drank from the bottle of wine and passed it back and forth a few times, making small talk and avoiding the issue that desperately needed discussion.

‘How did we get back to this?’ I said eventually. ‘We said no, then we offered that compromise: you and me don’t touch. Because we aren’t even into women, never mind… this ickiness.’

‘I agree,’ she shrugged. ‘but he gave us solid incentives. We do it, and he buys me a car, and he pays for your honeymoon. I’ve had shags for worse promises than that.’

‘But they haven’t involved me,’ I reminded her.

‘I still think mine’s better. I desperately need a car for work, but a holiday isn’t essential.’

‘It’s a gesture, Rachel. You know as well as I do he can’t really afford it. He’s stretching himself just for one night of fun that’ll never happen again.’

‘The question is – my question is – what am I prepared to do for it? If it means… touching my own little sister.’

‘More than touching. The things we normally do to ourselves, we’d be doing them to each other. Think about that.’

We fell silent again. Before he offered the incentives, the choice was either a point-blank refusal from us ladies, or the compromise. We didn’t expect the decision-making process to drag on. Eventually, we looked to the rest of the group for a solution. You can imagine the excitement it caused.

In preparation of something happening, and we made it clear this wasn’t a guarantee, we undertook some due diligence. Rachel affirmed she wasn’t sleeping with anyone outside the group and came back with a clear STI test. We then made her a group member to become more comfortable with seeing each other naked in sexual situations. She soon became part of the furniture, regularly masturbating with us and sleeping with both Thomas and Steven, but not yet Ryan.

Tiff and Samantha, meanwhile, offered us individual lessons in pleasuring the same sex, including fingering, oral and strap-ons. They even taught us tribbing, although they admitted it was probably too advanced for our purposes. While Tiff taught me, Samantha would instruct Rachel, or vice versa, but no sisterly contact would happen until we both agreed.

I’d dabbled with the other ladies in the early days, purely experimentally. I didn’t want a girlfriend and I wasn’t bi-curious. Even Fiona and I drew a certain line when we squirted with funnels.

‘Did you bring your envelope?’ I asked, passing back the bottle of wine, now half-empty.

‘Got it in my case. You?’

‘Same.’

The consensus favoured a hidden‑choice reveal or, as it was known among us, the Yes-No Thingy. On the wedding night, each of us would be given an envelope with two cards inside. One stated Yes and the other No. We would stand back-to-back so we didn’t influence each other, then produce one of the cards. It didn’t happen unless we produced a double Yes.

No matter the result, there was one up-side. It had made us talk one-on-one like we’d never done before, whereas I’d always chatted with my brother on a near-daily basis. It was almost certainly because I was two years older than Ryan, whereas Rachel was six years older than me. Being closer in age translated to a closer bond.

And not only were we chatting more, we’d reached an unprecedented level of candour. The back-and-forth questions ranged from heavy topics such as How do we handle any awkwardness afterwards? to What happens if he gets one of us pregnant? We also opened up about our sexual interests and preferences: If you squirt on your period, does blood come out? and Seriously Rachel, you like getting anal more than giving oral?

It wasn’t a dealbreaker, but since neither of us had checked that day, I asked, ‘Are you on your period?’

‘I think it’s finished. You?’

‘No.’

‘Good.’

Through these conversations, and with help from Tiff and Samantha, we had a game plan if it went ahead. Nobody wanted a half-hearted attempt, so we’d loosely choreographed a show. The pregnancy question always lingered in the background, but we’d assured each other our respective oral contraception had never let us down.

‘If all three of us were opposite genders but the same ages,’ I pondered aloud, ‘do you think the two older brothers would be having this conversation?’

‘I don’t think they’d entertain it.’

‘I don’t either. Even with a car and a holiday on offer.’

After another drink of wine, she added. ‘Maybe if the sister offered them blow-jobs for a year.’ As she handed back the bottle, we both let out a little chuckle, cutting through the atmosphere. But the levity was short-lived as she changed the subject. ‘Are you wet?’

‘Not really. Why do you ask?’

She pulled up her dress and gently fingered her clit through the material of her panties. ‘Should we maybe, you know, start the engines running?’

‘Here? In front of you?’

‘What if we don’t get wet?

‘You know Tiff calls it Pavlov’s Pussy: the flow always starts when the group does.’

‘Anyway,’ she shrugged, ‘we’ve watched each other doing this before, and having sex.’

‘Yes, but only in a group, not one-on-one.’ She started anyway, settling into a gentle rhythm. ‘Real talk: are you implying it’s a Yes?’

‘Real talk, Rebecca: I’m implying nothing, but even if it’s a No, we’ll still be playing with other people.’

I could tell she really was implying nothing, and I thought there was no harm in warming up. After a few seconds, I pulled up my own dress and started playing through the material. Not long after that, the fingers outside her panties became fingers inside, and I almost immediately followed suit.

As I hit my stride, I knew I’d need to stop short of an orgasm so I didn’t waste my squirt. I would need it for later. In any case, the session was cut short as Jack pushed the door wide open.

My sister and I immediately removed our fingers and let our dresses fall back into place. We were doing nothing he hadn’t seen a hundred...