Last summer, during the Independence Day festivities (pre-firework BBQ, very Americano), my grandpa met my little bro’s girlfriend for the first time. While he tried to hide it, his face screamed “GRANDDAUGHER-IN-LAW SPOTTED!” They are teenagers, but my grandpa, married by 21, met my grandma at his age, and was sure to remind my little bro after the party. He told me in private (oldest, enjoyer of teasing), that she reminded him of grandma.
I’m surprised I have never seen this trope in manga before.