The House of Windsor kicked off 2020 with a shake up that left the world shook up. Prince Harry and Meghan Markle announced they'd be stepping down from their posts as full time working members of the royal family and relinquishing use of their HRH titles. To top it all off, the Duke and Duchess of Sussex decamped to Canada for the foreseeable future, as well.
There are still a ton of questions remaining about what comes next for Harry and Meghan. First and foremost, royal watchers are wondering what their last name will be now that they're no longer working royals. Royal surnames are a bit confusing, mostly because it's quite common for them not to have one. When Archie was born, Harry signed his legal name, which is His Royal Highness Prince Henry Charles Albert David, Duke of Sussex, on the birth certificate. While in school and in the army, Harry went by Harry Wales. He used Wales as a stand in last name because his father, Prince Charles, is the Prince of Wales.
Upon welcoming their first son into the world, Meghan and Harry revealed Archie did, in fact, have a surname. They revealed their son's name to be Archie Harrison Mountbatten-Windsor. For those not completely obsessed with how all this royal stuff works, this surname may seem like a completely random choice. Mountbatten-Windsor, however, is the surname chosen by Queen Elizabeth for her direct descendants "on occasions when they needed a surname."
Most royals with HRH stylings opt not to use a surname. Now that Meghan and Harry will no longer be using their own royal titles, they may take Mountbatten-Windsor as their own surname. For the time being, however, they're still be casually referred to as the "Sussex Family." Harry and Meghan could choose to adopt this as their family name, just as Harry used Wales as surname when he was a child. Prince William and Kate Middleton's eldest children are enrolled in school as George and Charlotte Cambridge, as their parents are the Duke and Duchess of Cambridge.
Since Archie's legal surname is already Mountbatten-Windsor, it seems more likely Harry and Meghan would choose that as their family name over Sussex. We'll just have to wait and see what these groundbreaking rules end up choosing.