Ludwika Karolina Radziwill was married twice, first to Ludwig of Brandenburg - youngest son of the Great Elector from his first marriage - and then to Karl Philipp, the future Elector Palatine. However, the first marriage produced no issue (much to her father-in-law's disappointment) and the second marriage produced three girls - Leopoldine (1689-1693), Maria Anna (1690-1692) and Elisabeth Sophie (b. 1693) - and a son who died at birth in 1695.
Now what if she had been pregnant with a posthumous son of her first husband, or the son from her second marriage had survived to have children of his own? As the sole heiress to the Radziwill Estates of the Calvinist line, she made for a rather fetching bride, and by my understanding of it (which could be wrong, admittedly) any son of hers would also be the holder of said estates once she died. What effects might this have on the future of the PLC, as well as the dynasty to which the boy belongs (Wittelsbach or Hohenzollern)?