Not a bad way of doing it I don't suppose and I don't mean to derail your suggestion but I have an idea of my own in regards to this

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Personly I'd like it if by clicking a small icon or using a certain keypress (ctrl-r for example) would toggle on and off a set of little icons for each hearthling, one for kin, one for party, one for unknown, one for known and you could even expand it with one for when you have marked someone hostile or other similar things. I like the idea of getting to know someone's face from reading a wanted poster and then when you toggle this on it shows a little icon for that. Then again the icons could be shown for a brief second alongside names.
One other solution might be again toggleable, perhaps give the hearthlings a glow, different colours mean different things? Might not work well at night though I suppose. Again you could colour code the names when they appear for a brief second.
I also have to say that I think that while adding more GUI-like things can lower immersion it is much more damaging when it comes to immersion, among other things, not to know someone from their face when your practically related to them and stood feet away, seems Loftar agrees with me luckily

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