None of these are official connections. You can not have a brother fraternity or sister sorority without giving up your right to be a single-sex organization. GLO's have special charters that allow them to "discriminate" against members of the opposite sex, and an official connection would endanger that.

pledge dads/big brothers
 

This tradition varies widely from campus to campus, and is usually done unofficially, as many National GLO's do not allow it.

When I took a pledge kid, I asked a guy to be my pledge husband. If I had a boyfriend in a house, I would have asked him, but I did not at the time, so I asked a close male friend. Some people ask GDI's, but I would certainly prefer a man in a house.

My pledge husband obviously becomes my kid's pledge dad. He buys her something with his letters on it, and takes her out on "pledge dad night."

He is then just expected to look out for her, in a way. For example, if she needed a date to one of our functions, she could call him and he would set her up. When he sees her at the bar, he buys her a drink.

I have pledge sons in three different houses, and including the fathers of my own kids, I have four different husbands.

It is just pretty cool for the pledge kid because she gets to have a connection with a fraternity on campus.

At my school we switch with different fraternities every semester. My big brothers are in Sig Tau and my little brothers are in Phi Kappa tau and everyone claims that SAE is our brother frat so who know.

At Mizzou we change it every semester. Second semester the guys serenade the girls to be their partner for homcoming the next year, and then first semester the girls serenade the guys to be their partner for greek week second semester. Who ever is being serenaded votes for which house they liked the best. That way we all get mixed up and get to meet a lot of other people. However, most houses here have a special bond with their neighbors. My best friend is a Chi O at another school and more than half of their candlelighting ceremonies are for Theta Xi's, or Lambda Chi's, and those two houses are on either side of them. When our house gets finished (we're a new chapter) we'll be next door to Sig Ep and most of their guys that I've met are already very neighborly! ;)

At the University of Washington its Pi Kaps as well

You girls should try a Theta Xi, we eat the whole Pi!

I am in a multicultural sorority on our campus and we do not have an official brother fraternity. We have a multicultural fraternity also on campus who is like a brother to us. It would be nice to have a nationally recognized official brother though. :D

Alpha Xi Delta's official brother fraternity is Sigma Nu because they helped our founders to organize and create our sorority, but we don't have SN's on my campus. My chapter is very close to the Sig Eps here and many of my sisters have married Sig Eps. The past six sweethearts in a row have been Xis, and many more before that. Last year half of my sorority was dating half of their fraternity. We also always had a lot of fun with them when we were allowed to mix in their house, so there's a lot of friendships between us too. We're both the biggest and most popular organizations on our campus; it's funny because on Bid Day we find out that many of our new girls have boyfriends who are rushing Sig Ep too! We've had a close bond with them throughout the year that I hope continues, but we also do mix and have friends in other fraternities. We aren't necessarily exclusive to just hanging out with the Sig Eps.

D Phi E and TEP used to have convention together, but that stopped a few years ago.

Why did you have convention together? And why did it stop?

Theta Chi and Sigma Kappa are suposedly tight nationaly. I don't know though. We've never had a mixer with them. Mostly cuz we don't have a house. A few of them said they wanted to though.

From 1971 to 1983, D Phi E and TEP held joint conventions. I don't know why they did it or why they stopped.

Actually at the University of Washington the brother house of the Pi Beta Phi's are the Beta Theta Pis......these UW theta xis are out of the loop...

As a pledge we learn that beta theta pi is are father fraternity and FIJI is our brother fraternity that goes for every theta chapter nationally.

FYI
 

That is not true. Zeta Phi Beta Sorority, Inc. was founded in 1920 as the sister organization to Phi Beta Sigma Fraternity, Inc. This is stated in both of our constitutions.

AEPhi has no brother fraternity nationally, and we are discouraged from becoming fraternity "little sisters" etc.

A lot of people think AEPhi is AEPi's little-sister sorority. I have heard that so many times... My response: "AEPhi: 1909. AEPi: 1913. You do the math." :D