My roommate went through the RW audition process this past fall. She entered the second round of auditions and needed to send in a tape, but as a Gamma Phi Beta, she could not identify herself as a member of the organization. So if she had to mention how she lived in a sorority or anything greek-related, like when we taped her in her bedroom in the house, she just said something along the lines of "I live in my sorority house, it's nice, now let me tell you about my life..." and we avoided letters and emblems at all cost. I think if your sister avoids identifying herself as an ABC, you should be ok, but then again its different with every org.

BTW-my roommate didn't make it past the second round