I've been searching the boards for something like this, and have not been successful. I know there is still plenty of time to select my bridal party, and I am holding off in making any decisions. However, one thing I am really torn over at the moment is that I don't think I want to have my sister be a bridesmaid. She and I have never been close, and whether she means it or not, anytime she offers me advice, it really seems like she is putting me down and belittling my choices. If she were my friend, I wouldn't hang out with her anymore, but I don't have that option. I have my best friend for over 15 years who will be my maid of honor - there is no question on that front, and I have one or two other friends that I am considering asking when the time comes. My concern is that it will cause unnecessary drama within my family if I do not have her as a BM, yet my bigger concern is that if I DO ask her, she will cause fights among the other BMs and make my life miserable by dissing my decisions on how I want my wedding day to be. Has anyone else had to put family in their Bridal Party that they didn't want to, or perhaps anyone you ended up including while having second thoughts? Thank you for any advice.

Re: Excluding family from Bridal Party
It's your wedding. Choose who you want to be in your bridal party.
I am sensing that not including her is going to cause more drama than including her. She asked you to be her MOH, which means even though you don't think you're close to her, she does think she's close to you. And you hit the nail on the head - she's your sister, so you're going to have to continuing dealing with her no matter what you choose. Another point to consider: are your parents paying for your wedding? I know that even if they are, they don't have a right to determine your WP, but leaving out your sister might have negative consequences with them as well that you have to consider.
I think if I were you, I'd ask her to be a BM, and then leave her out of as much of the planning as possible. She'll feel like she's included without feeling like she needs to comment on all of your plans. You've known your MOH for 15 years - so she likely has some experience managing your sister's craziness. Tell her to politely shut her down, or to let you know if she is becoming unruly to the other BMs. And bean dip her on everything other than her dress.