How can I get close to my boyfriends little sisters who like modern kpop?

So, ive been dating my handsome man for about 7 months now (hehe~) and his little sisters are kpop fanatics! I used to like kpop a looot when i was younger, and watching them dance and listen to kpop brings me back to when i used to do nothing but love kpop. I listened to kpop from years 2007 to 2014 (im 19yrs, theyre 18,17), but my boyfriend says they only like todays kpop, which i stopped listening to, i think todays kpop is kinda just typical ^^;

But i really want to get closer to them. I auditioned for a kpop show kpop star 4 times, never passed, and performed at a talent show doing kpop (2ne1 dance). I kinda wanna tell them about it, but i wouldnt want to seem like im bragging.. what should i do?