I mean she kinda had the right to cuz imagine some random stranger is hanging out with your brother and going to unidentified dungeons which you have a bad experience with it cuz it caused the death of your teammates.
So in a way she was trying to protect her brother and remember her parents died when she was young so she doesn't know how to properly protect her brother bc she wasn’t taught how to but to get stronger and protect her brother so she did have the right to antagonist the fml even if it was annoying to u(bw im not trying to make this sound rude so if it does srry)
im glad the sister is not antagonizing mc anymore...because she was mad annoying