Some added info about QV's other sibling, her elder half-brother:
Queen Victoria's half-brother, Carl, 3rd Prince of Leiningen, made a marriage that, while not a morganatic marriage to Countess Marie von Klebelsberg (even though Marie did not come from a princely family)
was a marriage that did not meet with the approval of family members. Carl was the head of the house,
and thus was in the position to accept his own marriage. The marriage took place at Amorbach, the seat of Carl's tiny principality) on February 13, 1829 but would end in divorce. Although Carl and Victoria maintained cordial and familial relations, they were not nearly as close as Victoria and Carl's younger sister, Feodora, who was married to another mediatized prince, The Prince of Hohenlohe-Langenburg. Carl - the brother of the Queen of the UK, as well as the nephew of the Belgian king - could have made a great match. But he fell in love with the penniless Countess in Coburg. She was hardly an eligible bride, but he loved her. Carl's grandmother, Duchess Augusta of Coburg, blamed her former daughter-in-law, Louise (former wife of Duke Ernst II of Coburg, and mother of Prince Albert) for the introduction. It was Louise who met the Klebelsberg family when she and Duke Ernst had visited Franzensbad. Louise had largely adopted the young woman - but did have her doubts about Marie who became her lady in waiting. When
Louise left Coburg following the failure of her own marriage, Marie transferred to the staff of the Dowager Duchess Augusta who futilely hoped that her grandson's infatuation had ceased. The Dowager did intervene - and Carl and Feodora went to England for a time -- there were discussions for Feodora to marry the Duke of Sussex's son, Augustus 'Este. But even in England, Carl could not forget Marie - and after his return to Germany,he "unwisely" married the unsuitable countess.The couple had two sons - but the marriage soon broke down -and ended in divorce in June 1848. The "fair and feckless" marie had become involved with a man known only (through Prince Albert's letters) as "her cavalier, Mr. Spare."In a letter to his brother, Duke Ernst II, Albert wrote "Marie Leiningen is in Rome and she lives in a poor lodging. Mr.Spare, her cavalier, married her lady's maid. A sad result of the theory of life which Charles (Carl) always preached, that
life was for enjoyment adn that the wisest thing was not to consider anyone else."