One Direction's Niall Horan sends video message to fan - watch
Melena Butera's sister Julianna filmed Melena singing along to the popstars' tracks at their home in Long Island, New York.
Watch Melina and Julianna's video below:
Julianna is hoping that Melena, who has Down's Syndrome, will be able to see the band when they head to New York's Madison Square Garden on December 3, which is close to Melena's birthday.
Julianna told The Sun: "I would always play the songs 'What Makes You Beautiful' or 'One Thing', then Melena started singing them.
"The next thing I knew, she was watching videos of them on YouTube and singing along to every song. She's just like every other 15-year-old who has a crush on this boyband."
Horan has now sent Melena a 12-second video apologising for not being able to see her, but adding: "Your film was absolutely brilliant. We know that you're a massive fan and all the boys send you their love."
Fans can track the campaign under the hashtag #HelpMelenaMeet1D on Twitter.
Watch Niall Horan's video below: