This was an interesting one, I thought. Although I do shudder at the thought of corporations using bodies like that, and it seems ripe for class-based exploitation (the bodies of the mentally injured poor used to house the minds of the wealthy deceased) that I don't think I could ever celebrate this actually happening, it made some interesting food for thought for the story to use memory transfers from dead people to time-share a comatose body.
It was presented as if Baby Martinez's brain somehow "fixed" itself by copying the three deceased neurotypical women, and that felt cheap.
The way that I read it, the particular disorder that Baby Martinez suffers from is some kind of brain disorder that affects the sense of self? Instead of seeing herself as a person that is her, she can only observe the world including herself from an outside perspective. Maybe I misunderstood that. But the way that made sense to me was that by interacting with these other minds in her body, the thinking patterns mixed enough to allow her to have volition. The people running the timeshare seemed to think that the minds would not coexist but it seems entirely probable to me that you can't just wipe a brain like a hard drive--there's always going to be something left over, the brain is going to interconnect those pieces and somebody new is going to be the result.
I don't think that the resulting person is Baby Martinez, nor is it the other three people whose minds were inserted, but rather a new person born from the ashes of those people. IMO all 4 people are dead and can be mourned, and like I said I would be worried about the potential for exploitation here, but I think it also marks the birth of a new person, sort of an accidental hivemind, and I think it's worth celebrating that birth even while mourning the deaths.