But unlike August and Ernest, Sienna boasts a title that neither of them have, and it’s not down to her royal connections.
Instead, it’s courtesy of her father, Edoardo Mapelli Mozzi.
Beatrice’s husband, also known as Edo, is an Italian count, which means all of his children will inherit a count or countess title.
The family has previously spoken about its standing, with Edo the “only male descendent taking the family into the next generation”.
That’s according to his father, Count Alessandro Mapelli Mozzi, who told the Daily Mail that as Edo is a count Beatrice “will be a countess automatically and any of their children will be counts or nobile donna”.
It means that, unlike many less high-profile royals, Sienna will have a title.
This comes as neither Beatrice nor Eugenie’s children would be entitled to British royal titles as they are not grandchildren of King Charles III.
Sarah Ferguson, Beatrice and Eugenie’s mother who is also known as Fergie, spoke about her pride for her trio of grandchildren during the podcast Tea Talks with the Duchess and Sarah.
Fergie told the broadcast that while Beatrice was away for the wedding of Crown Prince Hussein and Princess Rajwa in Jordan last week,
She said: “I’ve managed to really have a bond with Sienna and guess what my bond is? I give her a little sup of my tea out of my tea cup… I put some cold water with it.”
The author also noted that Beatrice wore her prized tiara to the wedding.
The item was described by the Duchess of York as a “beautiful” item, which was given to her by her former mother-in-law Queen Elizabeth II.
