How Can Sweden and Prussia Form a Dynastic Union?

[MarshalBraginsky]

Realistically, since the first option may be a bit flawed depending on how determined Kristina of Sweden refuses to marry, would a marriage between Ulrika Eleonora or Hdvig Sophia to Frederick Wilhelm I of Prussia in 1710 to 1713 be more realistic that can also go along with a "War of the Swedish Succession"?

 

[von Adler]

If Gustav II Adolf lives longer, I doubt Kristina would convert. And he can make her marry, as well. In 1642, Brandenbrug would be the junior party, and I suspect the Swedish council would demand that any children be raised in Sweden - in fact, that might be the only way to placate the peasants in the Riksdag.

 

[MarshalBraginsky]

By which Gustav Adolf would not get a bullet lodged in his neck, thereby surviving for a while longer, right?