Something similar happened to me. My best friend and I went through rush together although we had different Rho Chi's. I was visiting the Panhel site for my school, and on the main page there is a slideshow of all the different sororities. My best friend's Rho Chi was on there! She had no clue which house she belonged to, and I somehow managed to keep it a secret from her. It turns out her Rho Chi was in my house so she would always come over and visit her with me.
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If the angels up above
Could hear us sing our song to you
They'd see that in our hearts
We're Pi Phi's from the start