Her sister is always desperately looking for ways to get away from the youngest. They are not close at all and it's hard to see siblings literally despising each other. Makes my mom heart hurt for both of them.
They are three years apart which is a big difference for children. The 11 year old is approaching those tween years. They probably will get closer when they both become teens or young adults. Maybe 8 year old is feeling that separation also and is desiring more together time. Keep those lines of communication open.