Ahn Sarang:
Not sure if it counts since it's couple cameo
Descendants of the Sun and Mr. Sunshine - FL's parents in Mr. Sunshine died while being part of Righteous Army and her uncle said that her parents would meet again in their next life and be happy together. They did in DOTS, also being part of an army
Yes, it is kind of related and the purpose is to find series where the writer or writers make a Universe.
emi:
4. twinkling watermelon + weak hero class 2
not sure if it fits the prompt but ryeon in twinkmelon plays the son of han yichan, who’s a very extroverted and silly boy. in whc2, ryeon plays a character very similar to han yichan, in terms of silliness with similar energy. and in one scene in whc2, when asked who’s he trying to be, ryeon’s character answers “my father”, and fans have theorized that it is a reference to his character’s father in twinkmelon, who also happens to be played by the actor choi hyunwook who’s also in whc
Well played!
Not really fits but topic stalls, so maybe you'll accept this:
Choi Won Young played Roh Jeong Eui's father in Hierarchy
Lee Do Hyun played Roh Jeong Eui's father as a teen in 18 Again
Choi Won Young played Lee Do Hyun' character's older self in Youth of May
As per the topic is difficult and you are finding a relation, let's go.
