Here's the hard thing about making the call: you can't say why they were cut, even if you know why. Often, it was just a numbers thing. That one hurts because the alum might know that 500 girls are coming back to the next set of parties and all she can think of is that the chapter liked at least 500 girls better than her daughter.
Or the real reason might be something sordid, such as her daughter has a horrible reputation--and the alum might not realize this. I know local girls who've been totally cut out of recruitment for photos they put on Instagram or Facebook. No one wanted to be the one to enlighten Mom that her daughter had posted a photo of herself peeing in a sink!