Meghan Markle and Prince Harry are taking part in a 24-hour TV show this weekend

Casual.

The Duke and Duchess of Sussex are officially back to work after welcoming their second child, Lilibet Diana, in June.

That’s not to say, though, that the couple have been keeping a low profile. From Harry’s TV appearance in a moving documentary honouring his late grandfather, the Duke of Edinburgh, to their hot off the press TIME magazine cover, Meghan and Harry's schedule looks to be the busiest its ever been – especially considering they've been balancing their hectic work commitments with a newborn and a toddler.

But after just a few short months away from public life, Meghan and Harry have made their first appearance as parents of two, having arrived in New York yesterday.

The Sussexes kicked off their trip with a visit to One World Trade Centre Observatory, alongside NYC Mayor Bill de Blasio and Governor Kathy Hochul. Following a quick outfit change (with Harry paying the most adorable tribute to Archie with his choice of accessory), the couple then met with UN Ambassador Linda Thomas-Greenfield to discuss issues related to coronavirus, racial justice, and mental health. Thomas-Greenfield later shared pictures of the visit on Twitter, calling her meeting with the Sussexes “wonderful”.

It's the couple's scheduled appearance for tomorrow, though, that's really got everyone talking. Yep, you read the headline right: Harry and Meghan will join a host of other celebrities in appearing on a special 24-hour TV show, broadcast live from Central Park. (Just your average weekend mini-break, then.)

The Global Citizen Live event, which will take place tomorrow, is "calling on G7 countries (the world’s wealthiest nations) and the European Union to immediately share at least 1 billion COVID-19 vaccine doses with those most in need".

Speaking about The Duke and Duchess of Sussex's involvement with the cause, the events organiser said, "Two of the strongest voices on vaccine equity are joining this once-in-a-generation event".

The Duke and Duchess of Sussex are far from the only A-listers on the guest list, though. Everyone from Billie Eilish to Kylie Minogue, Ed Sheeran, Elton John and Jennifer Lopez will be performing at the landmark global event, which will be hosted from New York, Lagos, Paris, Rio, Los Angeles, London, Sydney and Mumbai.

While it's not exactly clear what the Sussexes' appearance will involve, the subject matter certainly isn't new territory for them.

Earlier this year Harry and Meghan penned a letter to manufacturers of the COVID-19 vaccine reading, "The COVID-19 pandemic has exacerbated health, social and economic inequality globally. The global vaccine rollout thus far further deepens these disparities, with the poorest and most marginalised populations most adversely impacted."

Harry also appeared at the GQ Men of the Year awards earlier this month to condemn the anti-vax movement, saying that the "mass-scale misinformation that creates vaccine hesitancy" is causing those most in need to miss out on the medicine that could save their lives.

Global Citizen Live will be broadcast on Saturday 24 September from 5.30pm on BBC One.