I never read that one so just checked last chapters. But isn't "Wolf Behind Bars" an Omegaverse world? Because this one isn't. That's a weird crossover. Also is their surname Kwon? Because all I know, their name is Han Kiyo & Iri (without a Surname). Shouldn't it be Han Jio instead of Kwon Jio?
Iri's real name is actually Kwon Tae-hyung, he told Han Kiyo in the side story of Wolves Behind Bars. Iri is the alias he used as the member of Black Agent during the Death Game investigation. Now that he has quit being a secret agent, he goes back to using his real name though Kiyo still call him with the alias since he's used to it. So their child name is actually Kwon Jio.
But you're right the crossover doesn't make sense since that universe is an omegaverse one and this one isn't haha. I guess the author just like Jio too much.
Yes, seems author-nim couldn't resist despite the weird crossover
Aww baby Jio cameo (Wolf Behind Bars)