The policy is our Phi Sigma Sigma National policy. The part that I was talking about is associated with the "Little sisters" and "Little Brothers" policy. I even spoke with my advisor for the sorority just to be sure and it's true. She said it's also on our National website
Phi Sigma Sigma
Even though other sororities exchange shirts with other fraternities we can not.
I hope this help if not please go talk to you Archon and Advisor.
Annice