Maybe the fraternity should expand their program? If there are maybe 75 guys- they should have 20 little sisters. It seems like alot of work for 6 girls and maybe the feelings would subside if there were other girls from other sororities too. But- I know you can't make the rules for the program- only the fraternity can. Lastly, maybe you and the other 5 girls should have a "little sister" night out- just you 6 - bond over some beer and pizza and maybe it will come out that everyone is feeling the same way you are and it can all be worked out!
Good luck my red hot sister!!
Sue