The service was also attended by Prince Charles, the Duchess of Cornwall, Prince Edward, Earl of Wessex and Sophie, Countess of Wessex.
On Sunday, Meghan, who previous year stood next to Elke Büdenbender, the wife of Germany's President Frank-Walter Steinmeier, was joined by the Countess of Wessex and Sir Timothy Laurence on one balcony.
The balconies of the Foreign & Commonwealth Office building are also much smaller than, for example, Buckingham Palace, when all of the royal family have enough space to stand together on one balcony at events including Trooping the Colour.
The royals will then be split up in order of precedence - so the Queen stood with the two future Queen consorts, and Meghan stood with the others.
That same month, royal expert Katie Nicholl said in an interview with Entertainment Tonight that the pair are "loving parenthood" so much that they might be preparing for bringing in a sibling for Archie.
The royal family attended a number of engagements to mark Remembrance Day this year.
The Queen joined her family at the Festival of Remembrance at the Royal Albert Hall.
During an outing on Wednesday to surprise military families in Windsor, Prince Harry reportedly asked fellow parents what it's like to add a second child to the family, reported InStyle. We will always be brothers.
He said: "We are certainly on different paths at the moment but I will always be there for him as I know he will always be there for me. As brothers, we have good days and we have bad days". Ahead, see morephotos of her full outfit.