What if, somehow, Louis XV only has a daughter living and has her marry Frederick II or one of his brothers as a way to preserve the Bourbon Monarchy. Is such a thing possible? If not, why? Bonus if you can find a way to avoid the French Revolution from this theoretical union.
EDIT: you can make this union earlier than proposed here, just please give an explanation.
Would love to hear explainations from you and your ideas.
At your service,
Catalanking