This sentence 

  HRH Princess Felicitas Cecilie Alexandrine Helene Dorothea of Prussia, (7 June 1934–1 August 2009), was fifth in an unbroken line of first-born female children that started with Queen Victoria's eldest child, Victoria, Princess Royal. 

 does not seem to make much sense. Surely the line to Felicitas is: Victoria -> Victoria, Princess Royal -> Wilhelm II -> William, German Crown Prince -> Prince Wilhelm of Prussia (1906–1940) -> Princess Felicitas of Prussia. i.e. They're not all female, although it is perhaps noteworthy that she is in an oldest child line from Victoria. Or am I missing something?