Well... Except Riona. She's been kinda pissed off with Quinn lately and will be even more after the kidnapping (unless Quinn dies *).
Rio has a speaking with Quinn about Quinn dont humiliate Rio as with tommy. looked like they make peace. i can imagine after this kidnapping, they will leave this whole drug stuff and ignoring each other
The lowest point between Quinn and Riona was the slap, which is very old stuff, though. Now it depends on how the kidnapping issue will be resolved, we'll see. Vinnie as villain catalyzes much of the responsibility, and unless Quinn decides to do nothing, hide the kidnapping and leave Riona to her fate, she likely will play a role in freeing her
i dont think Quinn have option to hide this. if mc like Rio, he will wondering where is she, why not answer her phone. if she is missing, should he call the police? if Quinn say no, than he should ask why? oh wait, but mc is dumb. ok Quinn can hide it very well

about the slap, i think the humiliate is worse than the slap for Rio. Quinn probably not consider Rio as a friend, Quinn personality "first of all what about myself" type Rio will be just second thought.
Rio have problems about Quinn how treats her. as she said to Cammy. and maybe it will be very stereotype, but i think the japanese culture admits the honor specialy highly, so the slap is one thing, but the emotional damage worth more
Quinn will likely hide the kidnapping for now, maybe she tells the MC is her route. Either way their relation will be very shaken.
i think she will want deal with it herself at first and only later will "ask" help from mc and/or maybe tommy (because it is about vinny)
Surely Quinn will hide the kidnapping; she has no reason to make the news known to those who do not already know about her affairs. But the question is will she alone or with others rescue Riona, or will the poor girl have to go it alone. I believe the former, the latter would be an undying guilt
I was thinking, the obvious choice would be to ask Tremolo for help, but then I remembered there's a path he's not friends with Quinn. Thinking further -- never played because I like Riona --, there may be a path in which you completely ignore both Quinn and Riona, and MC's reaction when he hears the kidnapping news would be "who?"
Anyway, since this is obviously a canon event to all paths, I think it's still the obvious choice to have the MC in it -- it wouldn't make too much sense to watch it in 3rdP/God's POV. How Mr. DPC will solve the issue when the MC is not their friend, it's his problem...
I just hope there won't be an Acting Lessons style Sophia's choice scene. Not really a good thing when at first; it would make me die from cringe if it happens a second time.
EDIT:
Well... It may be so, but I don't think money's the issue here... He may ask for the money as a symbolic gesture and punishment, but I think what Vinny wants is to get rid of Quinn messing with his business. Also, though your money solution makes sense in the abstract, I think it would be such a simple solution that would kill all the drama. Besides, if there's one path wherein someone was injured or even killed and another where nothing like that happened, it will create such a mess in the game's development... Please, don't give Mr. DPC any ideas to delay his updates even more...
PS: yeah... I know it worked in Acting Lessons, but then were just one or two chapters 'till the end... Imagine five or six chapters like this...
well, we lost Mona, so we can lost Rio too. my favorite is Rio so it will be sad for me, but no matter, the fact, there is a way for losing her.
maybe dpc want deal with the whole kidnappen stuff on eazy way. going to vinny and buddy (i hope it is the name of the partner of Quinn's father) and they will just speaking and dealing like the hots should party with diks or alfas.
dpc just end the Jill route with some mc's inner thought what is very cheap. dpc can just giving a scene about Quinn go to vinny and come back with Rio. like when Quinn's stuff got stolen so she have to sell the stuff on 2x price. mc not really have anything to do with it. if he is on Maya and Jojo path, Quinn refuse the help with the blood.