Daniel's sister -- Hazel.

[Crabski]

I suspect this bit of commentary was simply recorded before some content was cut, and Frictional overlooked it.

Perhaps at one point in the development cycle there were other encounter-able NPCs Daniel could choose to aid, and thus would have influenced the loading screen text excerpts regarding Hazel.

Or maybe earlier in development Agrippa was encountered much sooner, and if Daniel created the optional tonic to help him out he'd have ended up having Agrippa's head in his inventory for a longer portion of the game, thus allowing time for the loading text blurbs to mention an event regarding Hazel in which Daniel saves her from something.

I'm pretty sure the commentary was recorded very late in the development (as in, in the past month or so), so I doubt the content it references was cut. Also, according to one of the commentary pieces, Agrippa went from being a very minor character to what he is now in a short period of time, due to changes in the level layouts and design needs. Take that as you may; it might also rule out the last theory there.

As for the second one, it's very possible IMO.