In the 1990s, Lord Archer proposed a succession reform bill that would allow the eldest female daughters to become heirs of the monarch of England (as well as allowing UK Royal Family to marry Catholics and other things). Let's say that reform was proposed in 1883, by Lord Cuthbert Matthias Kenworthy, 9th Baron Strabolgi, instead, and under a wave of support by suffragettes and so on, cleared the Lords and the Commons and become a Law.
Princess Royal Victoria would the become the heir of the British Empire (as well as German Empress for a couple of months in 1888, due to her marriage with the brief progressive Kaiser Frederick III). She would become Queen Victoria II, but she outlived her mother by only 7 months, so, after she died in August, 1901, her son, Kaiser Wilhelm II, German Emperor, would become King William V of the United Kingdom and the British Empire.
Would the Kaiser/King be able to avoid the Great war, now against France and Russia only?
If Russia still declares war to Austria-Hungary, because of the same Serbian issue that started WWI in OTL, would France and Russia stand a chance against the British and the Germans together under the same King?
Now, let's say the French put a heroic defense against the Germans coming from East and the British coming from the West, so war is still going on when 1917 comes, and the Bolsheviks are still able to overthrow the Tzar. And, let's say that Grand Duchess Olga Nikolaevna, older daughter of Tsar Nicholas II, married her cousin Prince Adalbert of Prussia, 3rd son of Wilhelm II/William V, in 1913, and they had a son in 1915, named Alexander (a good German, English and Russian name). With Princess Olga living in Berlin (or London) she wouldn't be killed when the Bolsheviks executed her family in 1918, so HER SON, Alexander Romanov, would be the RIGHTFUL HEIR OF THE RUSSIAN EMPIRE.
Then, after the British and German forces take Paris and force France surrender, they march against the Bolsheviks and retake Moscow around 1920, with Olga and Adalbert son becoming Tzar Alexander IV of all Russias, with his father, Prince Adalbert becoming his regent, as Alexander would be only 5 years old.
So, by 1921 you would have the British Empire, the German Empire and the Russian Empire all under the same Hohenzollern Royal Family. What would be the geopolitical consequences of such a massive worldwide empire, especially as you had the rise of the United States and Japan as world powers happening as well?
