Their soulful voices - as well as the big hair-dos and glittery gowns - had people comparing them to American divas The Supremes.
Raised by Samoan parents in Auckland's Grey Lynn, Ms Yandall grew up singing in Sunday school and in the choir at the nearby Pacific Islanders Presbyterian Church in Newton.
An older sister - Caroline, who died a few years ago - originally had them as a quartet, but after she married and moved to Australia, the younger siblings continued as a trio.
At the family home in Grey Lynn, a tapa cloth has been laid out for the singer's coffin.
She is surrounded by dozens of family photos and awards she and her sisters - now Pauline Prictor and Adele Paris - picked up over the years.
A nephew pops his head around the corner and at seeing his late aunt - dressed in a beautiful dress - he looks at his mum and aunt Adele and says: "I knew you'd put her in sequins."
The sisters roar with laughter.
Ms Paris smiles and says they wanted to "take her back to the 70s".
Ms Paris said Mary was the shortest and the tiniest, but had the biggest and strongest voice of all of them.
Within the extended family and close friends, she was known for her love of music but also for her love of God.
Asked to describe what she was like as a youngster, Mrs Prictor laughs.
"She was a ratbag. Mum would send her down the road to get butter and milk. Back then they had an account at the local dairy and at the end of the month you'd pay off the account.
"Mum would get an account that said butter, milk ... and lollies."
Ms Yandall will be farewelled at the Pacific Islanders Presbyterian Church in Newton tomorrow at 10am.
