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.

With Father's Day here, there's no doubt Kate as well as Prince George, Princess Charlotte and Prince Louis, will want to make it a very special one for Prince William

The Princess of Wales paid a touching Father's Day homage to William, celebrated as their children's "Papa", with moving "before and after" photographs. Two pictures shared of Prince William with his children in Norfolk accompanied by the endearing caption: "Happy Father's Day,