Isabel Rose, the telegenic heiress to one of New York's best-known real estate dynasties, has always had an ability to make her publicity wary family squirm. In 2005 she published a novel, The JAP Chronicles, in which she took aim at the Hermès-clad, charter-plane-flying set whence she came. (In a mostly positive review, Kirkus Reviews called the novel's characters "shallow, mean, self-centred, ruthless and resentful".)

Rose, 48, is a fixture on the New York cabaret scene, performing an Ann-Margret-inspired act at nightspots such as Joe's Pub and 54 Below.

A 2014 video for her single "Trouble in Paradise" showed her cavorting around in a rhinestone-encrusted romper from Patricia Field, flanked by a trio of drag queen backup singers, as she sang about how she wouldn't wind up as anyone's trophy wife.

But recently, Rose has been in the news for something with considerably larger stakes: the gender transition of her 8-year-old child, Sadie (formerly Samuel).

On 24 February, shortly after President Donald Trump signed an executive order that rolled back federal protections for transgender students, Medium published an open letter by Rose that was addressed to Ivanka Trump.

In it, Rose asked Ivanka Trump to take a stand on behalf of parents like herself. She pointed out their similarities.

"We are both from prominent New York real estate families, we both attended private all-girls schools and went on to earn degrees from Ivy League colleges, and we both married smart Jewish men and now have young children," Rose wrote.

Isabel Rose with her husband and two daughters (Sasha Arutyunova/ The New York Times) (Sasha Arutyunova for The New York Times)

Then, she issued a directive: "Ivanka, put yourself in my Jimmy Choos for a minute. What would you do if you were me? Because I know exactly what I would do if I were you: I would take my father aside and explain that failing to protect innocent children's rights to use the bathroom of their choice is wrong and unfair and un-American."

Within hours, the letter went viral, generating hundreds of comments that ranged from profoundly supportive to utterly horrified. It was reposted on the website of Harper's Bazaar. CNN commissioned a follow-up piece, in which Rose gently picked apart some of the more stinging commentary that had come her way, noting that there is a subtle but essential difference between giving a child permission to express who they are and engaging as a parent in "indulgent behavior."

At gay and transgender benefits around town, Rose arrived in her Isabel Marant trousers and the Row blazers, and was greeted almost like a folk hero – a Jessica Chastain look-alike who had spoken truth to power and put her social position at risk on behalf of a cause that needs powerful allies.

Rose didn't hear directly from Ivanka Trump, but Governor Andrew M Cuomo called and congratulated Rose on the letter. Last week, Rose even met with the president's education secretary, Betsy DeVos. Rose said she pleaded for protections.

Darting around Lower Manhattan, Rose was amiable and self-deprecating about what she has been through. At a benefit for the Family Equality Council, one of the hosts began talking about how miraculous having children is. "Except when they're unbelievably annoying," Rose interjected.

She noted that what is most remarkable about her family is how unremarkable they are; that change (or what she calls the "reversal of expectations") is simply the most reliable fact of life.

"I don't understand the tendency to catastrophise," she said. "I see it and the only conclusion I draw is that it produces adrenaline. It makes people excited."

But in a country where transgender people are routinely killed, it's hard to believe it can really be this simple.

Even for Rose – a person with wealth and privilege – there are relatives who have not always been comfortable with the choices she made. Not to mention people on the right, who are excoriating her for what they believe is the ultimate act of indulgence.

Supportive friends have questions of their own, as they wonder how she will balance the public demands of being an activist with the private responsibilities of being a parent.

How does she talk honestly about her child without opening her up to danger, and without making her into a representative she is not yet ready to be?

Sadie has slowly transitioned from boy to girl (Sasha Arutyunova/ The New York Times) (Sasha Arutyunova for The New York Times)

There are also Rose's own ambitions and desires, which can sometimes be hard to separate from the brand of activism she has chosen to pursue. She is, after all, a person who proudly calls herself "the second cousin twice removed of a drag queen" – a woman who requires no orchestra to break into song. And that comes with attendant complications too.

In 2002, Rose was the star and a writer of an independent film called "Anything but Love," which centered on an aspiring cabaret singer named Billie Golden who lives in Queens, watches Eartha Kitt enviously through the window of the supper club she works and fends off her the opprobrium of a mother who says: "You live your life as if you're in some kind of technorama musical."

"Technicolor," she corrects.

Of course, in real life, Rose did not grow up in Queens but on the Upper East Side of Manhattan.

Her father, Elihu, is a real estate scion and retired professor of military history at New York University who serves as the chairman of the Park Avenue Armory.

His family is largely responsible for the building and development of Stuyvesant Town and Peter Cooper Village, and they have donated much of their fortune to local cultural organisations such as the New York Public Library, Carnegie Hall, the Museum of Natural History and Lincoln Center, all of which have areas named after them.

Even at Central Synagogue – the congregation frequented by prominent families like the Lauders and Tisches – they loomed large, from the cheques they wrote, to their black-tie seders (a ceremonial meal).

As parents to Isabel, Elihu Rose and his wife, Susan, were determined to be completely supportive. "That's how it is with all of our children," Susan said in a phone interview this week. "There was never any other way."

Still, there was no question, that Isabel – despite her diplomas from Yale (summa cum laude) and Bennington (master's degree in writing) - was an unusual family member.

She is a performer. And performers can be her lowly accompanist.

And, in fact, there was a guy whom she both married and divorced soon after that. "Sometimes we have to learn good judgment by experiencing the repercussions of bad judgment," Rose said. Then came the novel, The J.A.P. Chronicles, which she subsequently adapted as an off Broadway show with one actress playing all six roles.

Guess who?

In 2008, Rose connected with Jeffrey Fagen, a tattooed Dartmouth graduate who spent years trying to be Robert Smith and now runs a clothing company called Panda Diplomacy.

First came a chat on JDate, in which Fagen recalled spotting her years before at the Williamstown Theater Festival. After that were drinks at Art Bar in the West Village.

On the fourth date, he asked her to marry him.

She got pregnant and said yes, trading the Plaza for the Park in West Chelsea, where she and Fagen performed a rendition of the Grease anthem "We Go Together" and were united in holy matrimony by Rabbi Angela Warnick Buchdahl of Central Synagogue, whom Fagen affectionately describes as the "only Korean woman rabbi in the world."

After the ceremony, Rose practically went into palpitations as a "senior member" of her clan said he was getting up to go to the bathroom, and she realised he was about to unzip at a urinal shaped like a male appendage.

"It was just like, 'Nooooooooo,'" said Rose, reaching her arm out, like a movie character in slow motion.

As fervent gay rights activists, Rose and Fagen joked to friends that evening that they were going to raise their baby gay but would "love him all just the same" if he turned out straight.

"What we weren't predicting was door No 3," Fagen said.

It wasn't just that their son, Samuel, wanted to play mermaids at age two, which led Rose online to numerous articles that described this as a typical predictor of "gender dysphoria," the mental state typically used to describe pre-transitioners.

It was also Samuel's refusal to smile for photographs with Lily and the violent tantrums that transpired while getting suited up for a relative's bar mitzvah.

"I'm a girl, Mommy," Rose recalled being told, over and over.

Friends didn't really know at first what the exact nature of the problem was. They simply saw a child, according to Fagen's close friend Mitch Epner, who was "totally withdrawn."

When Rose began to express the belief that Samuel might be transgender, friends doubted her. (More than a few also wondered privately: Why does the dramatic stuff always happen to her? "Isn't that the question," she said. "I don't know.")

Even Fagen did a certain amount of blaming his wife, which she found surprising given that he was, as she described it, "a rocker with a master's degree in poetry."

"All I can tell you is that I went through all the permutations people go through," he said.

So Rose took the good-cop role, becoming the confidante her husband wasn't ready to be.

On vacation in Palm Beach, Florida, she took Samuel, then around 4, to the Lilly Pulitzer shop and watched with curiosity as pink poplin turned a depressed child turn into a happy nymph. Back in New York, they watched David Bowie videos and went to the set of Rose's video, where the first introductions to drag queens like Hedda Lettuce were made.

Rose hoped to show her son there were many ways one could be a boy, from wearing metallic face paint to putting on green wigs and high heels.

Unfortunately, this didn't really work with Samuel, who was alarmed by Rose's compatriots and utterly uninterested in Bowie. Nor did it assuage the concerns of friends and relatives who argued at the time that Rose was "indulging" her child and pushing ever closer to the great trans abyss.

Throughout, Rose waded through confusing studies and heard troubling statistics about trans people attempting suicide. Attending another bar mitzvah, in Huntington, New York, in March 2014, the concern became more immediate.

Before the reception, the family was in their room hotel and Rose went to take a nap. When she woke up, Samuel was in front of the mirror crying and Fagen was on his knee, asking what was wrong.

The response: "I want to burn my face off."

"Until that moment, I never really understood the profound discomfort," Fagen said. "How does any child that young learn to hate themselves so much? After that it was, whatever it takes."

The first person they were going to have to come out to was Rose's eldest daughter, Lily, who was then 12 and had been somewhat in the dark about all of this.

But thanks to an iPhone and the miracles of family sharing plans, she learned the extent of their dilemma without even being told.

"My mom and I have the same photo stream," Lily, now 15, said one day after school a few weeks ago, while seated across from Rose in the den of the family's 5,000-square-foot sun-drenched apartment underneath a giant Marilyn Minter portrait of a high heel. "I was going through the pictures and I saw some of my clothes, but it wasn't me. So I was a little confused."

Maybe angry too.

"I was in middle school," she said. "You want to be normal and fit in. So I had to take a step back and say, you know what, this is not about me."

Together, the family embarked on extensive counseling at the Gender & Family Project at the Ackerman Institute for the Family, where gender-divergent children and their siblings and parents attend sessions together and then split off into peer support groups.

One early concern for Rose and Fagen was how to embrace their child's transition and not have her become a Real Housewife in miniature.

When the girl formerly known as Samuel suggested that the new name be Jasmine, a line was drawn.

At this point, Fagen was arguing that if parents get to name their son at birth, they ought also to be able to pick the second one five years later when she emerges as their transgender daughter. Then his child approached with the name Sadie, and Rose was able to broker a peace offering.

As Sadie's hair grew out, Rose felt it was time to clear things up quickly and definitively.

First, she placed a photo on Facebook of Sadie attending her first ballet class and allowed people to talk among themselves. Then, she took her daughter to Central Synagogue, where Buchdahl announced that the two were coming up to the bimah (a raised platform) to sing.

As Rose saw it, this was a good way to say: "Yes. Done." But it also was embraced by the synagogue's leadership, who thought standing behind the family sent a powerful message about what religious institutions can be.

"I don't want the religious right to be able to speak for God with a monolithic voice," Buchdahl said. "I understand that there will be interpretations of certain sacred texts that make this challenging for some people to accept, but I think it's important that we interpret the revelations with the moral compass of our day. And my understanding of our sacred texts is of a God who loves children, in all the ways they are made."

Sometimes, people ask whether Sadie's "transitioning" means she has already begun surgery or taking hormones.

Fagen patiently explains that those issues are years away, and that for now what has changed are "wardrobe and pronouns."

Given the confidence Rose showed at temple and on Facebook, perhaps the letter she published on Medium shouldn't have come as a surprise.

But it did to Susan and Elihu Rose.

"Well, that was crazy," Susan said, chuckling. "Eli and I were down in DC. We came home from the Smithsonian museum of African-American history, we were totally pooped, and I said: 'My God. Look at this amazing letter.' I didn't know Isabel was writing it. I didn't know anything about it. Then Eli said, 'Oh my God,' and he mentioned that he knew someone who knew Ivanka and maybe they could pass it to her. The next morning I sent it out to friends, especially friends with marginalised children who might be gay or transgender. I think it's just an inspiration."

Lily had a more complicated reaction. She asked her mother if she realised she had outed Sadie.

While the administration at Sadie's elementary school accepted her last year with the awareness that she is transgender, there hasn't been an explicit conversation with members of her class.

Fagen, asked whether he worries about his wife's openness with the world, and all the publicity about their daughter, said: "Absolutely. Every day."

"That's why you sometimes have to tie my string to the chair," Rose said.

Which was keenly self-aware, though it doesn't really answer the question of what might happen should Sadie decide as an adult that she wants her medical history to be private. How will she feel about what is for the world a mere Google search away?

Alternatively, if she decides she does want to talk about it publicly, will she feel the power of her story has been blunted by all of the adults who saw fit to tell it before she could?

But that's later.

For now, Sadie is merely a second-grade girl who loves science, likes math, thinks English is OK and hates history. She wants her mother to come home earlier, she wants her dog to sit still and let her pull its tail, and she wants to appear in the family photo with everyone this afternoon.

And that didn't used to be the case.

Also, a cupcake would be nice. From Billy's.