Our Kore groups were assigned at the beginning of the semester by the New Member Educator, and we stayed in those Kore groups all semester. She made sure to split up cliques and roomates within the older sisters - so it was good for all of us, we were all getting to know different people. I think it would have been cool to change them around maybe once or twice during the semester, but we didn't do that...
Having to furnish proof actually became one of the most fun part... like asking the guy at TCBY to sign an empty yogurt cup, trying to squeeze into a photo booth at the mall, or stealing a cup with letters on it from the fraternity whose party you went to (we returned it... honest!). One Kore group went to see the Chippendales and had pictures as proof!