They have enjoyed each other's company since even before JLo tied the knot with Ben in 2022 - and the year prior, were all smiles during a Disney World outing with the 13 Going on 30 actress.
Not only are they close in age, but Emme and Fin have long been know for their similarly experimental fashions and hairstyles.
The teenager (left) has developed a strong friendship with their step-sibling Emme Maribel Muniz (right), Jennifer Lopez 's 16-year-old, who uses gender neutral pronouns. Pictured in 2022
Speaking on the TODAY show last year, Lopez - who is also a mother to Emme's twin Max - opened up about the move to having all their children under the same roof.
Fin also has a sister, Violet, 18, and brother, Samuel, 15.
'It's been, like, a really kind of emotional transition, but at the same time all your dreams coming true,' she said.
'It's just been a phenomenal year. Like, my best year I think since my kids were born.'
In December, a source also told ET that the blended family enjoys spending time together thanks to the children's close bond.
'Ben and Jen's kids get along super well, and everything has been easy and seamless on that front, which has been really nice for them,' they told the outlet.
'Ben and Jen Garner are also in a good place. They have a mutual understanding that their children come first and are committed to that.'
Garner and Affleck split in 2015 and finalized their divorce in 2018, but maintain a friendly relationship.
Not only are they close in age, but Emme and Fin have long been know for their similarly experimental fashions and hairstyles. Both pictured in 2021
In December, a source also told ET that the blended family enjoys spending time together thanks to the children's close bond. Emme and Fin in 2022
Fans on social media have also for years remarked at Emme and Fin's 'inseparable' friendship, dubbing them 'BFFs'.
It is understood that the pals also attend the same school, with Fin sure to have helped Emme adjust after their move to Los Angeles from Miami, according to Hola!.
Lopez first publicly introduced Emme's pronouns to a crowd at the LA Dodgers Foundation's Blue Diamond Gala where they both performed in June 2022.
'[The last time] we performed together was in a big stadium like this, and I ask them to sing with me all the time but they won't,' the star said onstage.
'So, this is a very special occasion, because they're very, very busy and booked and pricey.
'They cost me when they come out, but they're worth every single penny because they're my favorite duet partner of all time.'
Last weekend, Fin debuted their new name before reading a bible verse to the congregation at Christ Church United Methodist in Charleston, West Virginia on Saturday.
The two were pictured together on a Los Angeles street with Affleck on February 12, with Fin sporting an eye-catching temporary pink hair dye
Garner and Affleck split in 2015 and finalized their divorce in 2018, but maintain a friendly relationship. Ben and Fin in 2022
The teen has been pictured with their new short cropped hair as early as February this year, but the funeral was the first time the top actors' child introduced themselves in public with a new name.
The memorial service, streamed live on as for Garner's father William Jack Garner, who died a week earlier age 85.
Following William's other grandchildren, Fin introduced themselves at the church lectern saying: 'Hello my name is Fin Affleck,' then read Chapter 16, Verse 8 from the Book of Proverbs: 'Better is a little with righteousness, than a large income with injustice.'
The two were pictured together on a.
The first hints of their new name came a few days earlier when Fin was pictured hugging their mother goodbye at their school bus stop in Brentwood, LA. In the photo the name 'Fin' can be seen embroidered on their backpack.
Last weekend, Fin debuted their new name before reading a bible verse to the congregation at Christ Church United Methodist in Charleston, West Virginia on Saturday
The teen has had a boyish haircut for years and has regularly been pictured in more masculine clothing.
The 15-year-old is just one of several celebrity kids who are finding their identities.
Actress Jamie Lee Curtis' daughter Ruby
'I'm in support of my daughter Ruby. I'm having them be a they/them,' Curtis said on the Today show last year.
'I'm going to just call them them. They/them, and they are doing great, they're settling in. I just — in my life, I never saw it in a million years that I'd have [these] couple days, and I'm very moved by the whole thing.'
Former Miami Heat NBA player Dwyane Wade also told the Ellen DeGeneres Show in February 2020 that he had since his daughter Zaya came out as transgender.