Blended family

My boyfriend and I each have two kids. Our daughters butt heads and clearly aren’t a fan of each other. His daughter shows it on her face whenever she’s around people she doesn’t like including her grandmother. I’m struggling with not having negative thoughts about the disrespectful attitude she’s having.

Would it be better for me to not voice my opinion on how I think something should be handled and just let it go even when I think it’s rude/ disrespectful? I don’t want to let her negative energy affect my relationship with my boyfriend, but she makes sure everyone knows when she’s not in a good mood because of who she’s around.