Peter Phillips’ teenage daughters Savannah and Isla Phillips team up with future stepsister Georgina on Easter Sunday

The Phillips sisters certainly don’t need to look far for role models when it comes to welcoming another sibling into the family. Peter Phillips and his sister, Zara Tindall, have a half-sister Stephanie Phillips, who is the daughter of their father, Captain Mark Phillips, and his second wife, Sandy Pflueger. Despite being significantly younger than Zara and Peter, Stephanie is close to the siblings and acted as a flower girl at their respective weddings.

It would seem Peter and Harriet are…