Virginia Shortland said her daughter Te Koha, who is 11, was very excited about the ''amazing'' response to the video, and quite humbled so many people had now watched it.
Te Koha has always had a passion for singing, even as a toddler, Ms Shortland said.
''As a parent, you just think it's cute. You don't really think it's going to be such a big thing for her, a driving force.''
When she was 8-years-old, Te Koha's proud father Gary bought her a karaoke set and the house turned into performance central, with other members of the musical whanau — professional singers among them — joining in.
''We've only been blessed with driving skills so we just ferry her around,'' her mother quips about Te Koha's vocal lessons, kapa haka and other performance events.
While she and Kapowairua are both self-confident and willingly take on leadership roles in kapa haka and other activities, Te Koha is naturally quite shy, her mum said.
That is hard to believe when she gets on stage and belts out, for instance, a powerful Etta James song.
Then, when the song's over, no longer channelling one of the queens of soul and R&B, Te Koha goes back to being an 11-year-old with a shy smile.
''I think she expresses herself though her voice,'' her mum said.
There is nothing shy about her 9-year-old cousin and singing partner, Kapowairua.
''Shyness is not something she suffers from,'' her mother Leonie Adams says.
As for the Facebook fame, ''It's almost unbelievable,'' Ms Adams said.
''Kapo thinks 'yay, it's fun', but I think she's fairly oblivious to how the size of that audience. She really has no comprehension of how many people that is.''
Her family musical heritage includes several older whanau members having been entertainers. In her own generation her sister Maria won Far North Idol two years ago, an older brother is a beatboxer and another brother has released a single.
Kapowairua likes all kinds of music but her and Te Koha's choice of busking a Jackson 5 number might show some family influence. When the King of Pop, the youngest of the five Jackson brothers, died in 2009 Kapowairua's extended family performed a tribute show.
That music is part of the family playlist so it's close to Kapowairua's heart — and it's a big heart for a little girl.
''Kapo's very outdoorsy, good at sport, but she just loves to sing, she loves to entertain.''