It comes after Fergie penned a heartfelt letter to her girls in Good Housekeeping magazine.
"Every day I thank the universe for allowing me to be your mother. You have always been the blood in my veins. From the time you were wee tots, you made my life complete," the Duchess wrote.
"I look at how full of humility, laughter and joy you are in your hearts, and I marvel at you both. Now, in you as mothers, I see strength, courage and steadfastness, integrity and goodness, and the way you embrace every challenge and moment.
"It is an extraordinary feeling when your child becomes a mother. Suddenly my little girlies have their own little ones ... such a feeling to get used to. But if I do cry or tear up as you drive away, it is only because I am so proud of you."
Princess Beatrice announced the arrival of her baby girl in September via an official statement to the royal family website which read:
"Her Royal Highness Princess Beatrice and Mr Edoardo Mapelli Mozzi are delighted to announce the safe arrival of their daughter on Saturday 18th September 2021, at 23.42, at the Chelsea and Westminster Hospital, London.
"The baby weighs 6 pounds and 2 ounces.
"The new baby’s grandparents and great-grandparents have all been informed and are delighted with the news. 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."
Meanwhile, Eugenie welcomed her first child with her husband Jack Brooksbank on the 9th of February 2021, with the news being confirmed by the palace.
The princess posted the photos of the family on her personal Instagram, which features baby August looking snug in the cutest outfit with his name scrolled in blue cursive on the back.
She lovingly captioned the post, “Thank you for the birthday love yesterday…"
Eugenie added: “I got the best present I could ask for!!”