CONFUSED On Duties!!!

I have a problem my sister is getting married july 5 and i`m getting married august 16? Mine is church her`s is outside how else can we make our guess not feel like it`s a repeat? Now the harder question? A girl i lived with 6 yrs. Refused to be in my wedding and later decided to be in my sisters. I am needless to say insulted. She will be one of my sisters three briddesmaids i will be her maid of honour! Whose job is it to plan her shower? I thought mine with bridesmaid help but she is planning shower at her mothers as well as stag which my brother was planning he is an usher what should i do and how should i do it without being rude even though were mad as hell? Please help