Sister Norway is a minor character, notable mostly for having the same uncategorizable relationship with Sister Denmark that their male counterparts have with each other. The primary difference is that as a woman (and a pudgy one at that), Sister Norway has plush breasts which both Denmarks have had the pleasure of groping.
Sister Norway has four siblings: Brother Norway (of course), Svalbard, Iceland, and Sister Iceland. Among the Nordic sisters, she acts as something of a "den mother." She may be Kven's literal mother, as it has never been specified which of the Norways is his parent.