Morality of interference with a Vengeance Hunt
Recently, I was doing my patrol (a task I have taken upon myself as opposed to being told to do so), when I witnessed a Sister (of unknown rank at the time) fighting against a group of fixers. Naturally, I jumped into the fray, taking one by surprise and crushing their skull on the spot. This, apparently, was the wrong thing to do as the Sister then began berating me for interrupting her Vengeance Hunt and taking away "her right to vengeance". As far as I'm aware, all Vengeances are held by all members of the Middle, with rare exceptions.
Am I mistaken? Was my interference the right thing to do, or should I have left her to deal with it herself? I know now that she was a Little Sister, of equal rank to myself, so I'm unsure which of us is misunderstanding the Book.
Follow up question, is it Moral to take out vengeances that other siblings have written? Or is it better to only assist others if asked?