[iamdave]

I would be surprised if there isn't language in the policies being underwritten today that would make such a thing possible... possibly even mandatory.

I think I'm misunderstanding, but when you say "make such a thing possible", what exactly are you referring to? The scenarios in your post I would think are heavily dependent on the considerations agreed upon in the policy between insurer and insured, so while Driver A may have a policy that sets limits on liability, Driver B may have a completely different set of considerations in the event of vehicle collision, what Driver C's car "sees" would just be supplementary, wouldn't it?