In 1660, after Charles II went back to England, two of his siblings died of smallpox: Henry, Duke of Gloucester (in September) and Mary, Princess Royal (in December). So, WI his other brother, James, Duke of York (the OTL James II) also died, let's say in December, together with Mary?
I'm assuming that James' first son with Anne Hyde, Charles, Duke of Cambridge, still dies as an infant. I'm also assuming that Charles II would still marry Catherine of Braganza (the political and diplomatical conditions aren't changed that much by then).
So, in this case, once it becomes clear that Catherine will not give him a child, then the legal heir of Charles will be clearly William of Orange (who needs an alternative wife ITTL). However, his sister Henrietta is married to Philip of Orleans. What could happen from it? How could diverge the relations between England, Netherlands and France? And how different would be the reign of Charles II now that his heir is clearly a Protestant nephew?
I'm assuming that James' first son with Anne Hyde, Charles, Duke of Cambridge, still dies as an infant. I'm also assuming that Charles II would still marry Catherine of Braganza (the political and diplomatical conditions aren't changed that much by then).
So, in this case, once it becomes clear that Catherine will not give him a child, then the legal heir of Charles will be clearly William of Orange (who needs an alternative wife ITTL). However, his sister Henrietta is married to Philip of Orleans. What could happen from it? How could diverge the relations between England, Netherlands and France? And how different would be the reign of Charles II now that his heir is clearly a Protestant nephew?