Really not possible. Would be basically giving the British Empire to the Germans, and there's no way such an act passes either of the two Houses of Parliament, let alone national opinion. Beyond that... there's a reason it took until 2011 to make that change otl, and that's with it not being an issue (on a technical level, given birth order) since Victoria's children.
Essentially, your idea is asking one country to give up sovereignty to another.