Jennifer Hudson and Ariana Grande line up for live Hairspray broadcast

Both star in the Broadway-to-live-TV adaptation – Hudson as Motormouth Maybelle and Grande as Penny Pingleton – and both will perform a duet in the live broadcast.

"We consider diva a good word, not a bad word," says Meron. "And it means that they're as generous as you'd want them to be, as much of a part of a company you'd want them to be. Everybody really has the same goal in mind with this show, and they're all working at the top of their game, and they're all working together."

Hudson had worked with Meron and Zadan before, on the television series Smash and on the Oscar telecast they produced. "So that was easy," Meron says. "And that voice, that talent, it just seemed made to fit like a glove."

In a curious twist it was Grande who contacted the production and asked to be involved. "Ariana has loved Hairspray from the time she was a little girl," Meron says.

Meron and Zadan have, among their other credits, become the go-to guys for live television musicals in Hollywood. In 2013 they successfully revived the genre with a live broadcast of Rodgers and Hammerstein's The Sound of Music and annually since with Peter Pan and The Wiz. Their success was also the catalyst for Fox to develop televised musical versions of Grease and The Rocky Horror Picture Show.

"We had this notion that we thought that people would really be interested in seeing a live musical on TV again, after not having been done for about 50 years," Meron says. "So, four years later, doing our fourth one, it's kind of very, very comforting to know that we weren't that crazy."

Zadan adds that the success – creatively and logistically – of each successive production has allowed the next to build on lessons learned in the last. "We've been able to do it year after year and learn from what we did to improve, to change, to experiment, which brings us to this place," he says.

We are sitting inside the cavernous soundstage on the Universal lot in Los Angeles – one of two being used for the broadcast – where Meron and Zadan have re-created the key sets for Hairspray, notably The Corny Collins Show. Outside is the Universal backlot which will be featured in the broadcast.

Of the live musicals staged so far Grease was the first to seriously blend indoors and outdoors but was mostly focused on indoor sets. Meron and Zadan say Hairspray Live! will use closer to 40 per cent of its airtime outdoors. To some extent, Meron says, that's why production shifted from Long Island to Los Angeles.

"It was the growth factor and the opportunity to actually go outdoors and make good use of the back lot here," Meron says. "It just seemed like a natural progression going from Long Island, where we were very confined to sound stages there, to be able to spread our wings a little bit more.  And this bodes really, really creatively well for what's to come after this, too."

Unlike their past projects, which they tackled for the first time in their live form, Meron and Zadan have history with Hairspray in that they produced the 2007 film version, which starred Nikki Blonsky, John Travolta, Michelle Pfeiffer and Queen Latifah.

Creatively the project goes even further back, to the 1988 film directed, produced and written by John Waters and starring Ricki Lake, Sonny Bono and the singer/drag queen Divine. The cult success of that film inspired the Broadway musical which came out in 2002 and won eight Tony Awards.

And Meron and Zadan are clear on that point: this project is a live performance of the Broadway musical. "With a few alterations that allowed Ladies' Choice [a song composed for the 2007 film] to be in there," Meron says. "But it is the Broadway show, and it's going to be just presented in this hybrid sort of manner."

Zadan adds the decade since the pair worked on the film has changed their perspective of its social commentary. "When we did the movie, we looked at it as a period piece," Zadan says. "Doing the show right now, every day on the set, it doesn't feel like a period piece, it feels like it's dealing with issues that we are dealing with in America right now."

To cast their heroine – the role of Tracy Turnblad is played in the live telecast by Maddie Baillio – Meron and Zadan auditioned around 1200 performers with only one caveat: "We knew we wanted to find an unknown girl, to have our Cinderella story in the midst of this Cinderella story," Meron says.

"Maddie walked in the room, and we all saw something that was incredibly appealing and incredibly Tracy," Meron adds. "And each time she came back, she said to us more and more that she should play the role, not literally, but in terms of her performance."

The pair will next work on a live musical broadcast of Bye Bye Birdie, planned for 2017. And Broadway, meanwhile, will reap the unexpected windfall of an audience whose musical appetite has been re-whet; the industry group The Theatre League reports that live TV musicals have lifted attendance numbers on Broadway.

"That's one thing that is mind boggling," says Zadan. "The whole country is now seeing stuff that they never have seen before. You'd see maybe a touring production but I don't think you'd ever see these shows: the sets, the costumes, the lighting. It's allowing the audience to see musical theatre in their living rooms like they've never seen it before."

WHAT Hairspray Live

WHEN SBS, Saturday, 7.30pm