This is really old, but I just wanted to add my 2 cents. I'm a member of Alpha chapter so I am a proud owner of the purple jumper
but I think what you're actually referring to is what we call "branding". Every sorority at Longwood wears jumpers, each sorority has "jumper days" (for example, we wore ours yesterday and were not the only sorority to do so since it was also the day of Lip Sync, it's just like days that the sorority picks to wear blocks, so everyone will be uniform). As for branding, what we want to do is to have a certain bag that we carry around so people will recognize us as Sigmas without us actually wearing our letters (these we can also carry to parties because it doesn't have letters). Another example of this is ADPi carries lion backpacks, so if we think of lions, we think of ADPi. We also have uniform blocks (although we're in the process of trying to get new ones).
I love the idea of the pullovers!