Maybe it WAS her sister, you never know! I don't know my T's sister, but I know she was at a meeting I also attended. Actually, there were many workshops and she was in a different one, but I wanted to see her so I peeked in when it was over. It was freaky. She looks like her, but not exactly. It was weird.
My T didn't used to like it when I wanted to surreptitiously find out all of this stuff about her and her family. She said to ASK her, instead, and wanted to know why I couldn't. She thinks I wanted/needed to get close to her, and that was my way of doing it. I've always done that with people who weren't really in my life. Idolizing them from afar.
I've seen my T's kids, too. I'm jealous of her daughter, though I'm close to my Ts age, not her d. I've got a lot of transference issues.

I think it helped me to post in this thread, though.

Makes me feel closer to my T. I still haven't called her about my session on Tuesday because I've got too many thoughts and feelings whirling around. I have to write them down and figure out what I'm going to say when I call her so I don't just say "um" and waste her time.