Proving that Marbs has always been the girls' first choice destination, the siblings look seriously happy and bronzed during a family holiday.
In one photo, Billie is squeezing Sam as they hug in the Spanish sunshine. Sam has changed quite a bit, but Billie still looks exactly the same!
Commenting on the snap, she said: "#tbt me and @samanthafaiers1, Marbella gals from a young age..." Referring to Sam's expression, she added: "Hahaha ur not impressed judging by the look on ur face!"
Billie then posted a second photograph on Instagram, which shows the sisters enjoying afternoon tea together.
"Hahaha two old girls drinking our tea with our backward caps ... #socool #tbt," she wrote alongside it. Aww, what cuties!
Although they are grown up, Sam and Billie still have a very close bond. They party together and even work together in their own shop, Minnies Boutique.
In July, Billie was the first of the sisters to become a mum when she gave birth to daughter Nelly - and Sam is a very hands-on auntie.
In fact, only yesterday Sam shared a cute photo of herself and Nelly as they enjoyed a cuddle together.