Stephanie Phillips, 23, the sister of Zara Tindall, 39, and Peter Phillips, 43, took to Instagram over the weekend to share the exciting news that she is engaged to be married.

Stephanie is in fact the half-sister of Princess Anne’s children on their father Captain Mark Phillips’ side, and was a flower girl at both Zara’s and Peter’s weddings. Stephanie’s mother is Hawaiian equestrian rider Sandy Pflueger. (Captain Mark Phillips, 72, and Pflueger, 67, separated in May 2012.)

Stephanie shared a sweet series of pics from a beautiful outdoor engagement shoot of her and fiance William Hosier, which featured a particularly impressive sapphire engagement ring. And it appears they’ve actually been engaged since early May, as she captioned the photos “09.05.21”.

Stephanie and William have been together for two years and, if the photos are any indication, these two are completely smitten with one another!

Stephanie was just 10 years of age when she appeared as a flower girl at the 2008 wedding of Peter Phillips and now-ex-wife Autumn Kelly. She also filled the role for Zara in 2011, aged 13.

While Stephanie may not be in the public eye very often, the keen horse rider is still close to her famous siblings, and grew up near Peter and Zara on a farm on the Gatcombe Park estate in South West England.