This is DPC we are talking about... Although my guess would be that he's going to make Zoey Vinny's sister. Remember that Zoey flashback that MC mentioned that Zoey had a brother that bought them booze (or something along those lines). So that makes me think that it's going to be Vinny. Also, MC has never met Vinny (and never even saw a picture of him), so it's a possibility.
Also DPC tries really really hard to be like George R. R. Martin and connect absolutely everything in the story in one way or another, just to get that shocking effect and it's getting predictable and annoying (hell, he even goes as far as going back and changing the story in the previous episodes so he can say he connected it and pretends he never changed it).
Next thing he'll do probably is that he's going to make MC's mom and Jill's mom best friends back in the day and have them made a weird promise/wish that their children are going to marry one day.
I don't see the problem with that. The parallels between MC's father's and mom's story and MC's potential romance plot with Jill were there since the first diary flashback entry. So, if their mothers were friends, which they probably were, I don't see it being 'annoying' or 'bad' per se. If you're on Jill's path, it only strengthens your bond with her and whatnot, if you're not, however, I don't see a reason why it would be detrimental or harmful in any way to your particular MC who doesn't do much with Jill.
However, I don't think I understand what you mean by the last sentence of your second paragraph:
(hell, he even goes as far as going back and changing the story in the previous episodes so he can say he connected it and pretends he never changed it).
All the 'twists' we've gotten so far, were in some way or form foreshadowed by the game itself, mostly through character dialogue or visual depiction (you even presented a potential 'twist' with Vinny being Zoey's sister which you based on a certain dialogue line from the game, we don't know if it will be true or not, but you didn't just think of it out of nowhere like dalli does 90% of the time). Therefore, I ask you a question what exactly do you mean by 'changing the story in previous episodes' when nothing's changed in the past that affects the future as it's all one big plot. If you have any examples, shoot, I will be happy to see them if they are there as you claim