I know it's Heonjae first, then Myeongil a month after.
I think the latest chapter is setting up Heonjae to live with Myeongil's siblings and then he'll eventually meet his uncle during the kids' 'observation day'. I can see the uncle connecting the dots from there and possibly manipulating Myeongil to harm Jingi by threatening the safety of his siblings.
Honestly wish Heonjae wasn't reintroduced so quickly... Like his last scene felt like an extended farewell but a few chapters later he's back as a homeless dude lol.
I haven't really processed the latest episode enough to make theories, but yours seem highly plausible, especially now that jingi and myeong-il's relationship looks like it's about to progress.
Hard agree on that heonjae sentiment, can't believe he just got out of prison after doing all that lol. Once again, he's not faced any consequences for his actions.

Does anyone actually remember their release dates? Heonjae's out of prison in the latest kr chapter, looks like myeongil actually wrote his house address on Heonjae's palm before they got separated.