How do tell my family not to got dargah (shrine)?

Assalamualaikum, I am actually a 14 year old boy, my family goes to dargah (shrine of a dead person) and I don't know exactly what they do but I think they might have committed shirk, I realised this all is haram and I repented from it, only Allah knows whether my repentance would be accepted or not and I am sure the next time I go to a dargah, I would try to avoid it but if I can't, I'll don't do anything there or just do acting, but my family does it, I am the youngest In my family so they may not listen to what I am saying. How can I get my family to not go to dargah?