I wasn't sure when I'd see you next, or even if I should tell you at all, but I feel like you'll hear anyway. Your sister stopped by to see me at the zoo yesterday, just after you left; It didn't go very well. I tried to be very straightforward with her, as she has some rather lofty assumptions, but I don't think she understood where I was coming from. I thought you should hear it from me though.
She mentioned wanting to get to know you better a few times and thought somehow I could help her, but I'm afraid, based on our brief discussion, she and I don't have a lot in common. I feel like I'm tattling, but that's not my intention. I want things to be smooth with your family, so I just hope things are different in the future. Maybe you two should spend some time together first? I honestly don't know where I'm going with this, but unlike your sister, I thought an open line of communication would be better.