Eighteen-year-old Melanie -- who was kicked out of this year's X Factor at the boot camp stage -- has confirmed that she is related to the Tipperary babe.
But the singer was keeping tight-lipped on her cousin's new relationship, stating: "That's not any of my business."
The Dublin native's dreams were dashed after she failed to make it to the final stages of the talent programme.
She now plans to move to London for her career and said: "I'm not going the reality TV route any more -- I'm going to go the artist route from now on."
Across the Atlantic, her cousin Cathriona White (27) has been making waves on the arm of actor Jim Carrey (50).
Photos emerged this week of the loved-up pair frolicking on a Californian beach.
The ambitious make-up artist relocated from Cappawhite in Co Tipperary to the US three years ago and is now said to be smitten with Carrey.
The striking brunette is said to have been dating the comic for the last month.
Cathriona, who left Ireland after studying to be a beautician, is currently living in Los Angeles and has worked on film projects since arriving in the States.
Her mother has said that her daughter is not involved with Carrey for the fame or fortune and the relationship is the real deal.
"It's quite difficult for her finding herself in the limelight like this. She's not doing any harm to anybody.
"She's not looking for fame or anything, she's just trying to live her life," said Brid White.
While she is said to be keen to build an acting career, she is also fiercely private and she even deleted her Facebook page after news of the romance emerged.
Cathriona, who is grieving following the death of her beloved dad Pat last month, is remaining in Los Angeles to work while Carrey is currently in London filming his new movie Kick Ass 2.
Carrey, who has been married twice before, split from actress and playboy model Jenny McCarthy in 2010 after five years together.
He has a daughter, Jane, from his first marriage with Melissa Womer, who at 24 is just a few years younger than stunner Cathriona.
Following his divorce from Womer, Carey married his Dumb And Dumber co-star Lauren Holly in 1996, but the couple split within a year.