Lin-Manuel Miranda brought his son on set for every 'Mary Poppins Returns' musical number.

The 38-year-old star - who plays lamplighter Jack opposite Emily Blunt's magical nanny in the highly anticipated sequel - has Sebastian, four, and 10-month-old Francisco with wife Vanessa Nadal, and he has revealed his eldest child loved loved seeing it unfold.

Asked about his highlights making the film, Miranda said: ''Coming from the theater, where the only thing that changes in the performance is the audience and your energy that day, to go, 'Okay, Thursday, we'll be shutting down Buckingham Palace and riding with 500 bicyclists. And Friday, I'll be dancing with the penguins,' those kinds of moments are really unforgettable.

''I brought my son to set, every time that we filmed a musical number, and to watch his eyes like saucers while daddy danced with what seemed like 500 dancers and bikers. I'll never forget the look on his face, as long as I live.''

The 'Hamilton' star also commented on the chemistry between Mary and his own character, and insisted that there has always been that side to the nanny.

He explained:''First of all, I would urge you to re-watch the first film. Burt has a 30-second rap about all of the women he dated before Mary Poppins. 'Jolly Holiday' is one big flirt between Mary and Burt.''

While Blunt suggested there isn't ''necessarily romantic'' intentions there, she agreed that was a flirtatious element.

She added: ''The enigmatic master plan is to set him up with Jane Banks, but I enjoyed playing the flirtation of it.

''They are such kindred spirits. Even though he's not necessarily magical, he gets it and believes it, and they're in cahoots with each other.

''I loved playing that chemistry with Lin, and I was so lucky to get to play it with him because he's so wonderful at bouncing it back and forth.''