Dadpaw
A #Dadpaw is a father of a later-in-life child, who is often mistaken for being the grandfather of said (younger) child. A #dadpaw is also likely to already have much older children, most likely teenagers or adult kids when he becomes a true #dadpaw.
Karen: "Is that your granddaughter?"
Abe: "No, she's my daughter."
Karen: "Oh, so you're a dadpaw?!"
Abe: "No, she's my daughter."
Karen: "Oh, so you're a dadpaw?!"