If Queen Victoria was the mother in law of Europe, King Christian of Denmark was the father in law. The six children of Christian IX and Queen Louise, photographed in 1882 at the occasion of their parents' Golden Jubilee. From the left: King George I of Greece, Empress Maria Feodorovna of Russia, Queen Alexandra of England, Crown Prince Frederik (VIII) of Denmark, Princess Thyra and Prince Valdemar.
Queen Louise of Denmark in Russian court dress. She was the consort of Christian IX, and two of her daughters were Alexandra, queen of Edward VII of Great Britain, and Marie Feodorovna, Empress of Russia. I suspect that this was painted to commemorate her daughter being crowned Empress of Russia in 1882.
King Christian IX of Denmark. The Grandfather of European monarchy. He & Queen Victoria - 3rd cousins through George II. Christian's children all married into powerful Kingdoms in Europe. He married Princess Louise of Hesse-Cassel & had 6 children. His eldest daughter Alexandra married Edward, Prince of Wales (Edward VII). His second daughter, Dagmar married Emperor Alexander III of Russia & became Empress Maria Feodorovna. Her eldest son became Emperor Nicholas II, last Emperor of Russia
King Christian IX of Denmark with all of his six kids. 1903. From top (starting left): King George I of Greece, Queen Alexandra of Great Britain, Crown Prince Frederick (later Frederick VIII of Denmark), and Prince Valdemar of Denmark. From bottom (starting left): Tsarina Maria Feodorovna, King Christian IX, and Princess Thyra.