Recording this here so that I don’t forget; I don’t have time to look into this right now.
I noticed that the ERG does not link who in the title sentence to the right predicate; it in fact links it to know (I think this is different from the discussion here?)
I also noticed that my Russian grammar does this correctly (don’t have a dmrs right now):
Now, I haven’t been specifically looking at this at all, so I am curious why it suddenly seems to be doing the right thing in my grammar. This couldn’t be a consequence to switching to append-lists somehow, could it? Because if it could, then it would be really interesting. (But of course it sounds more like something to do with clausal complementation or extraction analysis…)