I don't recall having my parents sign a financial responsibility form for AOII. We also had sisters whose parents did not know they were members.
Please take the advice of the other women also. Have your parents check out the greek life sections of the university's website, and also check out the parent's sections on the organization'a national webites. I know AOII has this. Here is the link:
National web address:
www.alphaomicronpi.org
Parent's section:
PM me if you need more info...