Princess Eugenie and her older sister Beatrice share a close bond so it is only fitting to see the former get emotional following the birth of her niece.

The 31-year old took to Instagram to congratulate her sibling on the birth of her baby girl with husband Edoardo Mapelli Mozzi. In the short but heartfelt message, she called the couple "dearest" and expressed her excitement to see their little bundle of joy.

"To my dearest Beabea and Edo⁣. Congratulations on your new angel. I can't wait to meet her and I'm so proud of you. We're going to have so much fun watching our children grow up. Love Euge, " she wrote alongside a photo of the couple.

Princess Eugenie also penned a lovely message for her niece in the same post. She hinted that she has already seen the newborn as she wrote, "To my new niece. I love you already and think you're just awesome from the photos." She then closed her note, "We're going to have so much fun ⁣together. Love, your Auntie Euge."

A sweet note from sister Princess Eugenie, who took to Instagram to congratulate “Beabea and Edo” on the arrival of their baby daughter. “I can't wait to meet her and I'm so proud of you,” she wrote. “We're going to have so much fun watching our children grow up.” pic.twitter.com/0bJWV4WG8i

— Omid Scobie (@scobie) September 20, 2021

Princess Beatrice announced the birth of her daughter with Mozzi on Twitter. She said the baby arrived safely and in good health thanks to the dedication of the medical staff who looked after her during the delivery.

"So delighted to share the news of the safe arrival of our daughter on Saturday 18th September 2021, at 23.42, at the Chelsea and Westminster Hospital, London. Thank you to the Midwife team and everyone at the hospital for their wonderful care," she wrote.

So delighted to share the news of the safe arrival of our daughter on Saturday 18th September 2021, at 23.42, at the Chelsea and Westminster Hospital, London.

Thank you to the Midwife team and everyone at the hospital for their wonderful care.

— Princess Beatrice of York (@yorkiebea) September 20, 2021

According to the official Royal announcement, the princess gave birth to a healthy baby weighing six pounds and two ounces. Her parents, the Duke and Duchess of York Prince Andrew and Sarah Ferguson, "have all been informed and are delighted" with news of their granddaughter's arrival.

"The family would like to thank all the staff at the hospital for their wonderful care. Her Royal Highness and her child are both doing well, and the couple are looking forward to introducing their daughter to her big brother Christopher Woolf (Mozzi's son from a prior relationship)," reads the announcement.

Princess Eugenie can share tips on baby care with her sister Beatrice since she too is a mum. She and her husband Jack Brooksbank are parents to seventh-month-old son August Philip Hawke.

Princess Beatrice and Mozzi wed in secret
Princess Beatrice and Edoardo Mapelli Mozzi opted for a very low-key and surprise wedding on Friday, July 17. David M. Benett/Dave Benett/Getty Images