Mackenzie died in 1982 at the age of 80, but her legacy lives on in the hearts and minds of those who knew her, or knew of her, which is where Easther and Parsons step in.
The women share a fascination for Mackenzie, bringing their research and perceptions to bear on a new play, aptly called Famous Flora, to be staged at Queen St strip club The White House.
"She was a woman who flouted convention and swam against the tide," says Easther.
"She didn't care for what so-called respectable people thought of her. Plus she was generous, decent and eccentric."
Parsons, who plays the elder Flora (Kate Elliott plays her in her younger years) agrees.
"I've always been drawn to colourful and eccentric characters and interested in finding out what makes people who live outside of what society says is the 'norm' tick. So I'm not judging Flora, not at all."
As the play's publicity tells it, Mackenzie went from being the proprietor of a frock shop to being the madam of a knock shop; quite a career arc for anyone, let alone a woman of Mackenzie's generation.
Salacious stories aside, what may surprise many is that Mackenzie was like a mother to her girls, earning a reputation for fairness and compassion to augment all the tales of hard partying and run-ins with the law.
"When I was thinking about writing a play about Flora I was questioned by someone in the theatre community whom I really respect, and he called Flora a disgusting woman," Parsons says.
"It hadn't occurred to me because I think she was, by all accounts, a great person and ahead of her time, and probably still is, considering the ever more conservative times we live in."
Although Parsons has been planning her own one-woman play about Mackenzie, she started chatting to Easther on the set of Outrageous Fortune about the famous madam and what a great story she makes.
The pair chose to collaborate on Famous Flora, although Easther says she doesn't know how the play will affect Parsons' plans for a solo show.
"Because she already had Flora in her heart and mind, she was the obvious choice," Easther says. "She's just perfect. She gets Flora, plus she's an outstanding actor. And she's so funny you'll split your sides if you spend more than five minutes with her.
"In the play, Yvette will be bawdy, saucy, sad and poignant. She'll make you laugh, cringe, possibly cry or at least get a lump in your throat. And I expect there may even be goosebumps."
• Famous Flora plays at The White House, 371 Queen St, Auckland, from November13-29, 6.30pm (noshowsSunday).