Like girl I don't know?

[Bob]

I went to school with her older sister and really like her younger sister. I don't know them and her younger sister goes to a different high school in my town. She is going to the local town college next year and I am going to a different one here but will be working in the cafeteria at the one she is at. How should I approach this situation?? I don't know her at all but see her all over social media.

[Ralph]

Umm, approach the situation? I guess if you don't know her, you should start by introducing yourself and get to know her. I wouldn't mention that you know her from social media, that might seem like you are stalking her. You could mention you've seen her in social media, but don't go into detail.
Personally, if you don't see much of her, I wouldn't think this relationship is going to go very far. Best of luck.