little sisters

[OnePlus69Is70]

I'm looking for arguments against fraternities having women's auxiliaries, ie "little sisters". I'm dealing with a chapter that has them, and I'm trying to convince them to do away with it before they're forced to.

Most of the women are wonderful, and it's great having them around and helping. They mostly either weren't bid by a sorority, or don't get along with the sororities on campus. (Or they're girlfriends of brothers, which turns into a real fun situation when they break up.) There are about 30 total, and probably 15 who are really active. The chapter has 23 total brothers, with about 17 who are really active. The little sisters meet separately, but they operate under our chapter director, and have a full committee system- they operate practically as a sorority on their own, with bigs and littles and everything.

The chapter gives three reasons for having the auxiliary:
1) These are the women who would be around the house anyway, so organizing them to help us reduces the work for us.
2) It frees us from having to deal with the NPC sororities, who would impose rules on us.
3) It keeps the women who hang around the house under control- we can get rid of one we don't like by not letting her into the auxiliary group.

My reasons for getting rid of them are:
1) It exposes us to liability; court rulings have held that a fraternity can be held responsible for the actions of a women's auxiliary group.
2) It's against national rules. (Not often a good reason for anything, but I thought I'd throw it in.)
3) Having the women around doing their work for them is making the brothers lazy- the women are expected to handle a lot of the responsibility for parties, and that isn't right.
4) It's created the impression on campus that they're a forority- which isn't half wrong. The male pledges and new female members all have big brothers AND big sisters.
5) It weakens Greek unity- we ought to be working with the NPC sororities.
6) It's disrespectful. The idea that the men need to keep the women under control (which is exactly how it's put) is mildly horrifying.

Can anyone bulk up my arguments, or give me a few additional ones?