This is my first play through. I checked the wiki and it seems that Heather Poe is the only person you can make into a ghoul. However, I did not ever encounter her and I think I may have progressed too far now for that to happen. Apparently she is supposed to be found injured in the clinic in Santa Monica. I checked every room in the clinic periodically as the story progressed but never saw her. I am now doing quests in Hollywood and have no quests left in Santa Monica right now. Did I miss my chance somehow? If so, that would be disappointing.

Could check the patient logs on the hospital PC to see if she died.

That is the one room I did not check on my first visit. I thought that with staff watching me I might get in trouble entering that room. I checked it not long after that and it was empty. That sounds like a helpful tip. I might try that if it happens again. I am near the end of the campaign so it doesn't matter any more for this play through.