Question for all my sorority girls!

[Greekgal1990]

Okay I am a sigma chi rush helper and brought out a friend who was a zeta to a party this weekend.
She ended up spending the night there, in one of the members rooms since her ride back had to take another person home who got sick. I know for a delta zeta this is against rules for them and can get them on probation, but I was told by a sigma chi that it was okay for alpha chi omega girls too.
what is the general standard on it is it ran by NPC, each chapter, or the sorority it's self, or what? I just know one of my friends may be in a lot of trouble, and if the other rush helpers are putting themselves at risk too. I want to be able to warn the girls who should and shouldn't be going up stairs at the fraternity houses with letters on them, that way nobody will be getting in trouble from a great weekend at sigma chi.

I am most concerned on the rules for, Delta Delta Delta, Chi Omega, Alpha Chi Omega, and Zeta