“You’re in them all day, from morning rehearsals until the after-parties,” she said.
The honor of Miss Golden Globe is also an openly nepotistic one. The press organization, which is made up of 85 active members, has given the role to celebrity offspring since the 1960s. Publicists typically pitch candidates, said Lorenzo Soria, the group’s president. “They will say things like, ‘Isn’t this one cute?’ ‘As you can see, this one is interested in theater,’” he said. They end up with a bunch of names and pick one or two.
The Stallones were an exception. They caught Mr. Soria’s eye last year, when they accompanied their father to the ceremony, where he won the supporting actor prize for the film “Creed.” “I remembered seeing the girls on the red carpet: elegant, smiling, fresh, happy,” Mr. Soria said. He called Mr. Stallone to float the idea. “I said, ‘Discuss it with them and let me know.’ And he said: ‘I don’t need to ask them. The answer is yes.’”
After some hemming and hawing that involved five publicists — welcome to Hollywood — the Stallone family declined my requests for interviews. I inferred that it had something to do with Ms. Flavin feeling protective and with Sistine’s handlers holding her back in advance of a publicity push surrounding her budding modeling career.
Sistine, at least for now, is clearly the star of this sister act. Sophia, a student at the University of Southern California, has more Instagram followers (293,000 to Sistine’s 279,000), but that may change soon. Last month, Sistine hired the P.R. agency 42West, which represents Kylie Jenner (82 million followers), and not long ago she signed with IMG Models. Sistine has already appeared in Teen Vogue and an Express ad campaign; Dolce & Gabbana flew her and a flock of other model-celebutantes to Milan Fashion Week in September, where she made a splash in a leather bustier and black lace leggings.
Stellene Volandes, Town & Country’s editor in chief, said that Sistine came onto her radar about two years ago, when she arrived in the magazine’s Manhattan offices accompanied by her mother. The visit had been set up by a mutual acquaintance. “I was impressed with Sistine,” Ms. Volandes said. “She was humble. She was polite. She sent a follow-up email thanking us for our time.” Ms. Volandes added: “You could look at that cynically, but, having met her, I think it was genuine. It’s certainly not typical.”
Sistine’s Instagram account finds her in various chic spots. There she is in Venice. Now she’s in St.-Tropez, club hopping to platinum-card spots like La Cave and VIP Room. In one post, she does a two-handed cheer from the stairs of a private jet, while Sophia, wearing a floppy hat, looks on. (Caption: “Goodbye London, Hello Ibiza!”)
All three sisters, sometimes in possession of a Pomeranian, make frequent appearances in videos posted to Mr. Stallone’s social media accounts. To the delight of his fans, at least judging by the comments, his daughters often respond to his goofy antics with down-to-earth eye rolls.
“Let’s do a video,” Mr. Stallone, 70, can be heard saying at the start of one, as Scarlet, seated on a bed looking at her iPhone, comes into view.
“No,” she says.
“Why?” he asks, and later adds, “Don’t tell me you’re getting shy on me.”
As Sophia told “Access Hollywood” about her father’s video hobby in a recent interview, “I don’t know about you, but I don’t want a phone in my face when I wake up first thing in the morning.” (I’m with you, sister.)
Serving as Miss Golden Globe — they will most likely rotate coming on stage, although that has yet to be decided, Mr. Soria said — may come most naturally to Sophia. She does not appear to be pursuing a career in show business, but she does have experience in the spotlight. In 2012, she had an old-fashioned debut at Le Bal des Débutantes in Paris, a diamonds-and-couture affair that also drew young women like Filippa Brandolini d’Adda, a descendant of Italian nobility, in Ms. Stallone’s year.
As for the teenage Scarlet, she may have the gait to beat on Golden Globes night: As a high school track star, she apparently goes by the nickname the Flash.
At least that’s what Mr. Stallone calls her.