Should i become friends with her?

You shouldn't think of it as stealing your friend, all though sometimes we feel that way. I think that you should not hold a grudge against her just for that but at the same time don't just befriend her because your other friends are. Give her a fair chance! Then, if you find that YOU like her, then become closer friends to her. Otherwise, don't be rude to her or you could cause drama in your group and make them choose.