I’m from the same culture and religion that I’m fairly certain you’re talking about & this is a tough one. My family is similar but has lightened up over the years. The only thing that concerns me really is that your sister will be extremely unhappy in her marriage. Idk the reasoning behind her arranged marriage (did she choose it or is she doing so to please your parents?). Either way, if she’s an open minded and accepting person, she will be miserable with a close minded, judgmental, uber religious person, especially once they have kids. I think it’s more important that before the wedding, she decide what she really wants for herself and her future & maybe you can be the one to help her?