This is a tragically hilarious story that i need an opinion on to make better?

So my 18 year old sister has been best friends with this girl whos 17 for almost 3 years now. Their entire family knows her. I coincidentally became best friends with her brother whos 15 and im 16 for over a year now. Its like our two familys just have the same genetics or something. But they also have a 14 year old sister whom ive had a huge crush on for more than a year now. Ive never told her or anyone because i thought it was weird because shes too young for me. So after some trouble between me and my dad, i moved to a different state 14 hour train ride away to my moms. (These people actually offered for me to move in with them). But my sister and her bestfriend were both already in kansas before I got there, and while she was temporarily here before she went back to her house, she told me multiple times how her 14 year old sister actually has a huge crush on me. That was the first time i heard anything of it. Now what should i say to her the next time i see her?