One of our main rules at rush was do not talk about any other sorority PERIOD. If a sorority cannot attract new members by presenting themselves with honesty and intergrity without back stabbing another sorority, they have very BIG problems.
JAM, I had a situation when I was an active with a new sister in another sorority bad mouthing my sorority. She didn't realize that I was sitting right behind her. Of course when I made myself known by standing up looking her in the face wearing my letters, most of her sisters had the common sense to be embarrassed. She however thought that it was funny and laughed in my face.

Of course, I had the last laugh when I brought her conduct to the attention of my friends in her sorority who happened to be on the Executive Board.

They assured me that what she had said was not the opinion of their sorority and apologized and promised that it would not happen again.
I think that the DG chapter president should bring this conduct to the attention of the ____ chapter president. At the very least, she will be embarrassed and apologize and hopefully, it will never happen again.