The advancement/experience move in Sagas of the Icelanders is written as follows.
When one of your moves targets a character that you have a relationship with, mark that relationship. When you mark four different relationships, erase your marks and pick an advancement from your rolebook.
When does a move target someone? For some moves, it's very clear, but for example does the Goði's Legal council (When you are asked to pass judgement on a legal dispute …) target the legal parties?
Given there isn't always just one: Is there a restriction listed somewhere that you can only mark one relationship at a time? You could have the chance to mark multiple relationships when they are all with the same target (which is explicitly a thing you can have) or when a move targets multiple characters.