Thats a good question, i havent tried that yet.
You are the one telling them exactly who to kill, and "why" theyre being killed. So im assuming if i hunted those specific people down, sooner or later I would see my guildie take them out
Sometimes it wouldnt work though, because a lot of the time the target is in another province (aka not in the oblivion game world). But sometiems they are.. so im gonna try that later