LONDON — Prince Harry’s fiancée, Meghan Markle, appeared for the first time at an official event with Queen Elizabeth II on Monday, highlighting the royal family’s welcome of its newest member just two months before their wedding.

The two were joined by other members of the monarchy, including Markle's soon-to-be brother- and sister in-law, Prince William and Catherine, Duchess of Cambridge, to celebrate Commonwealth Day at Westminster Abbey in London.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Wearing an off-white coat and hat, Markle, an American actress, was seated behind the queen and next to Princes Harry and Andrew. The couple walked in behind Prince William and Catherine, passing a troupe of dancers performing outside the abbey.

The Queen is joined by other Members of The Royal Family at @Wabbey as they celebrate #CommonwealthDay. pic.twitter.com/Vjy5gIgDZU — The Royal Family (@RoyalFamily) March 12, 2018

The queen is the head of the Commonwealth, a group of 53 nations around the world that are largely former British territories. Around 2,000 people were expected at the interfaith gathering, including Prime Minister Theresa May and British singer Liam Payne.

While this is Markle’s first time at an event together with the queen, she has had a busy few months since her engagement to Prince Harry in November. The former “Suits” star has had a preview of her future role as a royal, with the two meeting organizations and the public in Nottingham, London and Birmingham as well as Edinburgh, Scotland.

“She is already effectively being treated as a full-blown member of the royal family, even if she hasn't married Prince Harry yet,” Roya Nikkhah, royal correspondent for The Sunday Times, told NBC News. “I think that gives you an indication of just how warmly she has been welcomed into the fold, but also effectively she is living as a member of the royal family.”

Prince Harry and his fiancée, Meghan Markle, left, arrive with Prince William and Catherine at Westminster Abbey for Commonwealth Day on Monday. Daniel Leal-Olivas / AFP - Getty Images

Known in the local press as the "Fab Four," Markle, Prince Harry, Prince William and Catherine are to meet with schoolchildren after the service.

At the end of last month, the four appeared on stage together for the first time at an event promoting the Royal Foundation, set up to coordinate the princes’ charitable activities. Markle spoke about how women need to feel empowered to make their voices heard.

Prince Harry, who is fifth in line to the throne, is to marry Markle on May 19 at St. George’s Chapel, a 15th-century church on the grounds of Windsor Castle. Around 1,200 members of the general public will be included in the wedding, which will feature a carriage ride around the town after the nuptials so they can greet the public.

Since her engagement to Prince Harry, Markle has been embraced by the British public. With a more casual manner than many of her fellow royals, she eagerly meets and hugs people during her engagements, an unusual gesture for royals in public.