Should I try again? Or should I just leave it? Any name ideas?

I want my little sisters to call me Akka (means big sister) or another name. My older step-sister is called Sissy. My youngest sister wants to call me Sissy also, but my family probably won't be okay with it. (especially my step-sister) I asked my little half sister to call me that but she said no. My baby (4) half sister also said no. and the parents don't support it- I am fully Indian and my dad is also, but the rest of my family isn't. I live in California and visit occasionally. I think they may be opposed to the Indian name... Everyone wants to call me a form of my name, but my younger sisters don't call me anything different and I would like them to. My older step sister who used to live with them is called sissy by them. So I just don't have a special nickname and I would like one because I believe it increases the bond. My step sister has said herself, my little sister doesn't mind her doing anything because she is her sissy. Is it wrong for me to want a nickname. I like Akka because it means older sister, but anything works. Do you have any ideas? Everyone calls me Sagar, so I don't want that. My name is Sagarika. Do you have any ideas for names which mean sister and are used in America. If not, do you have any nicknames? Do you think it is wrong for me to want a nickname? I feel left out often by my little sister and my step sister because my little sister imitates everything she does and always wants to be with her and that makes me feel bad because I feel I am much nicer to her. I try to do whatever they would like because I want to develop a friendship/relationship with them. Do you think I should try again or just leave it?