According toMyka Meier, an etiquette expert and the author of the new bookModern Etiquette Made Easy, a lot of it depends on the tricky subject of their HRH titles.
PerQueen Elizabeth’s announcement on Sunday,Harry and Meghan will “not use their HRH titles”when they stop being working members of the royal family. (Meghan, 38, and Harry, 35, will still be Their Royal Highnesses until this spring when they officially step down.) However, the statement from Buckingham Palace was perhaps intentionally vague, only saying that they will “not use” the titles, not that they had been stripped of the HRH titles.
“It all is a bit murky,” Meier tells PEOPLE. “Now that they are keeping their HRH titles but not using them, the order of curtsy would stay the same as it has been since Meghan married into the family.”
Meghan and Harry pay their respects to the Queen.ADRIAN DENNIS/AFP via Getty

According to Meier, once Meghan married Harry she would have to curtsy to anyone who outranks her, which includes the blood princesses (those born into the royal family, like Harry’s female cousins) andKate MiddletonandPrince William. However, that changes when she was with Harry and she then takes on his rank, which means that she outranks all of Harry’s cousins but not the Cambridges,Prince Charlesand the Queen.
Harry, meanwhile, will continue to outrank his cousins as long as he remains at his place in the line of succession. As Meier notes, there have been no announcements made yet on if Harry will step down from the line of succession.
The logistics of Meghan and Harry stepping down has beenconfusing even for the royal aides, who on Monday had to walk back on previous guidance that the couple would now be known as Harry, Duke of Sussex and Meghan, the Duchess of Sussex instead of the Duke and Duchess of Sussex.
While Harry, Meghan and the royal family sort through the new etiquette surrounding their new situation, Meier did have clarification on if Americans need to curtsy to the Queen in general.
“If an American meets the Queen, they technically do not have to curtsy or bow because as Americans that is not a custom of ours, and instead they could choose to simply shake hands to show respect to her,” says Meier. “If you go that route, just wait until the Queen extends her hand and then follow suit.”
“That being said, many Americans still choose to observe a traditional British greeting of a bow or curtsy,” she explains. “Either option is fine and deemed appropriate. Meghan, however, would always curtsy to the Queen because while she is American, she is a member of the royal family.”
While Meghan is likely following the rules when it comes to her in-laws’ etiquette, Meier does highlight two other non-royal women who married into the royal family and have already become etiquette masters.
RELATED VIDEO:Princess CharlotteShows Off Her Picture-Perfect Curtsy to the Queen on Christmas
“The Duchess of Cambridge is impeccable at all times, poised and very kindhearted,” Meier says when asked about which royal she thinks has the best etiquette. “She carries on a lot as a mother of three and wife, and also as a senior royal where she is a patron of many charities and non-profits which rely tremendously on her … all while being the epitome of grace.”
Yui Mok - WPA Pool/Getty

As for which female member of the royal family has the best curtsy, Meier also has her own top pick:

Modern Etiquette Made Easy: A Five-Step Method to Mastering Etiquetteis out now wherever books are sold.
source: people.com