JEALOUS?

We didn't think that Emily, being older, would get so jealous of her little brother. Boy were we wrong! We are so mean for asking her to pick up her stuff or do anything else that we would normally ask her to do. She constantly tells us to quit yelling at her--we have made a conscious effort not to yell--just use our normal voices, but for some reason she views it as us yelling. I am so glad that Grandma Marilyn has been here after school everyday to play 20 games of UNO and let Em help her make supper. Any advise anyone?