I just remembered The Borgias did the same thing, only worse. At the start of the show, Rodrigo has three sons and one daughter.
By season three he's yelling how Cesare is his only son.
Fandom: ???
Fandom: Gioffre?
Fandom: Little Gioffre who everyone loved? There was a whole plot point in season 1 about marrying him off to improve relations with Naples. Juan's dead and he had it but coming but what happened to Gioffre? Did he die in the plague that hit Naples and you didn't mourn him like you're whining about Juan?
Fandom: You just forgot about him, didn't you?*
Fandom: ....
*fandom makes a milk carton graphic with Gioffre's pic on it*
Fans pay attention to these things!