( not related with Peter but I need help)

just walk away without saying a bad word with mean boys and girls. and stand up to a bully if they harm u.

It is unfair that your sisters are doing that, but is there any reason for it? আপনি could ask them about it and maybe they would tell আপনি something about the cousins that আপনি are unaware of অথবা something. If there is no good reason for it, try going to your parents and explaining the situation to them. Unless there is some factor আপনি don't know about, your sisters are just being mean.

I'm not really sure what to do about the people calling আপনি names, don't let it get to আপনি though. People usually tend to bully অথবা call names when they feel that আপনি threaten them somehow (like maybe they don't like that আপনি are smarter, আরো athletic, funnier, etc. then them and that scares them) অথবা they are insecure themselves.