You could always start an alumnae chapter of XO. I would have thought there'd be a chapter near you. Aren't you in Dallas/Forth Worth? I kow ther are 13 or 14 Chi O chapters in TX, I would think there'd be at least a few alum assoc's especially in the bigger cities.
I know you can join a Panhallenic Alumnae assoc. but I do not know about another groups. I know in college they don't usually allow "social afiliates", but sometime you can get in unoffically by being good friends with someone I guess. Hmmmmm...interesting!
Hope you find one!
