When Frederick I needed an heir in 1740s, aside from choices like a Danish prince, Adolf Frederick of Holstein-Gottorp etc. the French candidate was Christian IV of Zweibrucken (1722-1775). What could his election cause and what would be necessary? A stronger France? A huge victory in the War of the Austrian Succession (I've been wanting to do a TL about a French victory for some time so maybe a different Sweden on the side?)