That girl, she's my auntie, really
I grew up calling her sister, but one day her aunt (her mother's sister) told me that I'm supposed to call her "aunt" and I was like What!!! Hell no!!! She's 2 years younger than me! I can't even call her "elder sister", let alone auntie
But I don't know, her mother is supposedly some distant relative (well maybe not too distant) of my maternal grandmother. I don't know exactly about the family relation but her mom worked for my mom's tailor shop and that's just how I knew her.
I haven't seen her again since I left for the US.