Younger people suddenly revealing that they are an unsuspected child of a protagonist is a common dramatic (or comedic) theme in fiction. As mentioned many times here, you can get plenty of good ideas for roleplaying game plots from fiction, but...
Just because something occurs a lot in fiction doesn't necessarily mean it's suitable for a game.
If you are considering throwing a twist like that at a PC, make sure the player is okay with it. Otherwise you're taking away their agency over an aspect of their character that may be deeply personal and important to their concept of who that character is. Some players may be fine with such a complication and embrace it, but others won't.
Commentary by memnarch (who has not seen the movie)
So..... Han walks out on the catwalk, shouts at Kylo, starts a big tense standoff with troopers pointing guns behind them, and Kylo.... takes his helmet off? That seems so odd. Like a "I want to humanize myself so you don't kill me" from the unstable Sith wannabe who hasn't shown any sign of being empathetic so far kind of odd.
Maybe there's something true in the conversation here? It could be a comic-based twist, like the big "Darth Vader is Luke's mother", especially since this comic isn't being written for just people who haven't seen the movies. But then there's the problem of "why's there a reveal going on at all" here? That sounds like extremely bad writing, but I don't recall overhearing anyone saying they disliked Episode VII. Depending on the movie dialogue, a twist like that just because that's what the directors want sounds like the sort of thing that could have torpedoed the ending and the whole takeaway feel of the movie.
Guessing at the movie aside, I'm amused that the name Kylo would fit the stolen name pattern. Maybe comic-Kylo's father is also named Kylo, so this Kylo took that name back and swore revenge. I wonder if Sally came up with this backstory info before or after creating Kylo. She was the one who asked about the GM letting Jim play
Han Xasha Mr. No-Name again after all.
Kylo Ren: Stop there. I want you to see something.
(No Name): What?
Kylo Ren: The face of a son.
(No Name): I don’t have a son. That, uh... I know of.
Kylo Ren: Not your son. Not your son! Do you recognise this face?!
Kylo Ren: You killed my father.
(No Name): It’s possible. I kill a lot of people.
Kylo Ren: You stole his identity.
Chewbacca: He does perpetrate an awful lot of that too.