fh sister as bridesmaid

Agreed - it's awkward to cut someone out as a bridesmaid, but since she asked to drop out, I'd let her out, and not back in if she changes her mind.

Definitely doesn't sounds like she's worth having in the bridal party if she's already brought on all this drama and stress on you. It's pretty lucky that she's willingly dropping out on her own so you don't have to have that awkward conversation to kick her out. But don't worry, this one situation shouldn't keep you from being able to form a relationship with her in the future. She's young, her and your FH will eventually work things out (as siblings do), and everything will be okay

She already said she doesn't want to be a bridesmaid so leave it at that. You cant make her do something she doesn't want to do.

Let her drop out. The way I see it, if she treats your FH this way, its only a matter of time before she tries to pull something on you. Have only girls that you know will fully support you, and not use their position in your wedding as any type of leverage for anything

I agree, let her drop out if that's what she wants. It sounds like she's in a somewhat tough position with her boyfriend, so she's probably very overwhelmed

Let her quit. You don't need that kind of drama. It was really nice of you to ask her in the first place. Sounds like she's not quite grown up yet. You'll be much happier without having to deal with her.