We are forgetting one very important character when it comes to the attempts to kill MC. This character has the experience, resources, craftiness and opportunity to pull off all three of them. That of course is Wilfred. Up until this update I was suspect of his motivation and loyalty but see that changing from a direct threat to the the MC to an implied or indirect one. I think he is very protective of Luna and Gracie though. He could easily have tampered with the brakes since no one else was there to see it, He could have a servant in his back pocket for the poisoning and he could have used his connections to arrange the assassination attempt.
Looking back at the whole dinner scene in the first act of the game, I found it a bit surprising (and also a bit suspicious) that Wilfred is not present for dinner. He just takes MC to dinner & disappears. Granted, Wilfred does not have any blood relations to the actual Family (but then again, neither does MC), and there's the saying "Family is more than Blood." (with Luna and Gracie always calling him "uncle" and him reminiscing about taking care of them in "Portend")
And like you've said, he might be just the person who could have pulled it off.
Though I'm not sure about the motive. I don't know about others, but it seemed to me from the beginning that Cordia & Wilfred clearly had (and still has) plans for MC, and trying to kill MC (against Cordia's wishes) with malice might seem contradictory.
Only reason that I can see Wilfred poisoning the MC is possibly in order to just test MC's actual resilience to poison. It may seem twisted and harsh method, but I'm somehow getting the feeling if Wilfred is the culprit, he already knew about the incident where Rina (MC's mom) tried to poison MC, and wanted to test it to compile his Family database (Which he compiles based on abilities and potential. Possibly for the next generation of 4 Serpents)
But of course, if that is the case, Cordia would definitely not approve, and I can only see him doing it behind her back (with Antonio saying "Mother was furious." to MC's poisoning when he wakes up, so I doubt she was in on it if Wilfred is indeed the culprit).
With that in mind,
HopesGaming I have one question:
1) It's been awhile since we've seen the whole Family having the dinner together, so any chance we get to see them dining altogether again (doesn't have to be dinner, breakfast or lunch I wouldn't mind also. I actually loved the interaction & conflicts in that scene in opening act of the game)?