BM Vent (Long Sorry)

i have had it! sorry for this vent but i am ready to explode. i have 7 bms - 4 of which are cousins. 2 are younger but my other cousin had us all and it was a nice gesture so i followed suit. i would have just had the older 2. anyway, my one cousin is incredibly narcissistic and selfish and has been a thorn in my side through this whole process. we have been sending emails all year about BM dresses and other things. Not ONCE did she EVER reply to any or call including apparently all of the shower planning. they even changed the date for her at the last minute bc she had a graduation party but didnt bother to tell any of the BMs when they set the date and then had the nerve to be late and make my other cousin late.
so today, the first email i EVER get with a week and a half to go is to inform me that she is bringing a date to the rehearsal dinner(never RSVPd by 6/1 and wasnt invited with a date) and is getting her hair done in NJ the day of the wedding?! first of all we gave #s for the dinner already, second of all if she is late the day of the wedding and ruins my day i will flip out on her. what do i even write back to her?!

This is tricky situation because it is family. How old is she and is her date to the RD a long-term boyfriend or just a random? If it is the latter, I would kindly tell her that since she is 2 weeks late with the RSVP and you never factored in a date, that you are sorry but she cannot bring him.

And regarding the hair, tell to be in LI at an earlier time so if she is late then she wont be THAT late...

I think you should explain to her how you are feeling (that she may be late, her lack of participation, etc.) If you wait until the day of the wedding you are adding unecessary stress on your self that you wil not want on your special day. Explain that it has seemed from her actions that she does not want to be a bridesmaid and then see her response. I hope everything works out for you!!!

i know it is tricky with family and i love her parents and wouldnt want to hurt them. shes an adult though (22) and she is so unbelievably rude & selfish and i feel like i need to let her know how much grief she has caused me. she is my only regret about my wedding. she was even rude to me when i asked her.
i dont think this is a long term bf but someone she's on and off (mostly off) with for a year maybe? ive only met him once.