The shared Instagram account for Kate Middleton and Prince William welcomed a trio of guest posters Sunday, when children Prince George, Princess Charlotte, and Prince Louis took the platform over. The occasion: Father's Day, with a post in tribute to their dad, the Prince of Wales.

After her cancer treatment, Princess Kate participated in the Order of the Garter ceremony again. The 43-year-old supported Prince William at the traditional event at Windsor Castle.

After arriving at Buckingham Palace by car, Kate and the children, Prince George, 11, Princess Charlotte and Prince Louis, 7, traveled in a traditional horse-drawn carriage down The Mall. Charlotte sat beside her mother, while her brothers faced backward across from them.