The Friedman sisters have been making art together since they were little girls. Their London childhood was chaotic — they were often left to their own devices — but the family’s four children found solace in storytelling.Now Sonia, 59, is one of the most successful theater producers in the English-speaking world. Maria, 64, is a celebrated actress and singer. Their sister is a scientist, and their brother, who died last year, was a violinist.Sonia and Maria have occasionally worked together over the years, but rarely with as much emotional investment as on the current Broadway revival of “Merrily We Roll Along,” which Maria is directing and Sonia is producing. The revival has been transformative for the show, which, despite much-loved songs by Stephen Sondheim, was a famous flop when it first ran in 1981, and is now one of the hottest tickets in town.On Sunday night the Friedman sisters’ production won a Tony Award for best musical revival, as well as acting prizes for two of its stars, Daniel Radcliffe and Jonathan Groff, and another for its orchestrations. It did not, however, win for Maria’s direction, which made their evening bittersweet.“My heart went into 2,000 pieces,” said Sonia Friedman, who has a shelf full of Tony Awards, but just wanted recognition for her sister. She said she had to step out of the theater to collect herself. “The little sister in me was in agony for an older sister who’s only ever held me and supported me.”A few minutes later, the sisters went up to the stage together to collect the Tony for the production, which Sonia dedicated to Maria.“Winning the Tony was fantastic, for Steve and for the legacy,” Maria said the next day. “Losing was painful.”But she also said that, during the Tony season, she had become friends with the other nominees, and admired them all. She particularly praised Danya Taymor, who won the directing prize for a new musical, “The Outsiders.” “I saw her work, and I think she absolutely deserves that,” Maria said. “I don’t have a feeling like I was robbed.”“Merrily,” with music by Sondheim and a book by George Furth, is a reverse chronological depiction of the implosion of a three-way friendship. The revival, which ends its limited run at the Hudson Theater on July 7, is both acclaimed and profitable — in other words, to quote a song title from the show, “It’s a Hit!” This week, the Friedmans plan to capture the revival on film.The two sisters discussed their long history with “Merrily,” and their even longer history with each other, in a joint interview over steak salads at Gallaghers, a century-old theater district haunt. The late-afternoon lunch — they had been up until the wee hours, first at a “Merrily” after-party at the Ascent Lounge, and then at a stars-plus-show tunes after-after party at the Carlyle Hotel — had been scheduled before they knew how their evening would go.They both said they saw the production as a tribute to Sondheim, with whom Maria had a close friendship forged through years of performing his work in England. The “Merrily” production had been planned before his death in 2021; Maria said that when he died, she thought about canceling, but was persuaded that’s not what he would have wanted.“As I started to work on it, in the room, I realized he hadn’t gone anywhere,” Maria said. “He’s in every corner of this piece. He’s in every molecule. And so the fact that it won best revival is beyond anything.”The two sisters are quite close. As children, Maria often looked after Sonia; as adults, Sonia has returned the favor, particularly during Maria’s two bouts with cancer. They are fiercely proud of each other, and also obviously fond of each other — whenever the conversation became emotional, each sister turned to the other for comfort. Sonia described them as “on a raft together.”Their childhood was, at best, unorthodox, and often completely neglectful — they say that, had they been born a few decades later, they would have been placed into foster care. Their father, a prominent violinist, left around the time of Sonia’s birth; their mother, a polymathic pianist, had no aptitude for or interest in parenting, and the children were largely left to fend for themselves when it came to basic things like finding food, or getting to school. They describe themselves as having been abandoned and disrespected; Maria referred to the children as “feral.”“We were four children effectively left to support each other, in every respect,” Sonia said. “Our schooling was inept. We often didn’t go. But what we did was make stories. We would improvise stories, and music, and dance.”By the time Sonia was 10, conditions at home were getting worse, and all three of her older siblings moved out for self-preservation — Maria was just 15 when she left.“There was this fissure, this tear,” Sonia said. “We don’t need to go into the detail of what happened in the home, but the relevant bit is that I had to lose myself in stories. I’d lost everything.”Sonia threw herself in her dollhouse, escaping into the dramas she dreamed up concerning the daily lives of her dolls. At one point, she was expelled from school for truancy; she says her life was saved by a community council that paid to send her to boarding school.Throughout her childhood, Sonia would tag along with Maria as the older girl got theater roles; as Maria began building a career as an actor, Sonia began imagining a life behind the scenes.They were both enjoying some success when they first collaborated professionally, in 1994, on “Maria Friedman by Special Arrangement,” a cabaret show based on songs Maria had first performed at a festival established by their father. Their brother played in the band; their father, with whom they were reconnecting as adults, was initially involved, but then died before the show transferred to the West End.There were other joint projects over the years — “Ragtime” in London in 2003, and “The Woman in White” on Broadway in 2005. But there was nothing like “Merrily,” a show that Maria has been connected to for three decades, and which she has now directed seven times.Maria’s relationship to “Merrily” goes back to 1992, when she starred in a production in Leicester; Sondheim and Furth were both alive then, and revising their work following the Broadway disappointment.Two decades later, Maria directed a student production of “Merrily” at a London drama school — it was the first time she had directed anything, and when Sonia came to see it, she not only cried, but also had a moment of clarity about her sister’s skill set as she watched actors devouring Maria’s ideas. “Dammit — she’s a director!” Sonia recalled thinking.Sonia saw the school production with David Babani, the artistic director of the Menier Chocolate Factory in London; the two decided to ask Sondheim for permission to mount a professional production, which he granted. That production was a success, and Maria directed subsequent productions in the West End, in Japan and in Boston before putting together the production starring Radcliffe, Groff and Lindsay Mendez, first Off Broadway at the New York Theater Workshop in 2022, and then on Broadway starting last October.“Steve wrote a masterpiece, and I have given everything I had to it,” Maria said. “I have given it my heart and soul and my thought and my brains and my experience, and it keeps giving me something.”Sonia has been with her all the way. “It’s the most personal thing I’ve ever done,” she said. “Because of the story of ‘Merrily,’ it forces you to look back on your life, and the choices you’ve made, the paths you’ve taken, the mistakes along the way. And if you’re producing this with your sister, you can’t watch it from the back of the auditorium and not track your own life through it.”The two reject the idea that they had set out to rescue the show, which Maria said would be “arrogant.” Sonia said she doesn’t even think of the original production as a flop, but as “a show that hadn’t found its path.”But they also said that the show’s intense history — it has always had a cadre of passionate admirers, even though it hadn’t quite worked — is much more present in the United States than in England. But as they nurtured it in London, they felt the pull of New York.“There was like this calling: Please bring ‘Merrily’ home,” Sonia said. “It deserves to be up there, in the lights on Broadway, as a success. It needed this redemption story.”Each of them said, even after years of seeing “Merrily” performances, it continues to resonate deeply. “It’s so sublime, and as we grow, I can’t listen to it, I can’t experience it, without having a deep, deep cathartic reaction,” Sonia said.Maria agreed, saying, “It’s about a lifetime, and ‘Merrily’ morphs with us,” she said. “It asks us, ‘How did I get to be here?’”