Kick future sis in law out my wedding??

I am so confused about what to do at this point. I have a bridal party of 6. We went for fittings in early Nov...gave them a deadline to purchase by Jan 18. Beginning of Jan, I sent out friendly reminder txts to see who had purchased and for anyone to let me know if they just couldnt afford to participate any longer which i would understand. Future hubby sis did not respond to the text. Fast forward to last week, i sent a text asking did she get her dress she tells me no and that she planned to order that wknd...never called or texted me to inform me that she did indeed order or not. I mentioned it to FH and he said well ill call and ask her, when i started to elaborate why it is important for bridesmaids to at least communicate with me he begin to get irritated and cut me off and just said I told u ill ask her....so I just left it alone cause i know its touchy cause its his sister. Im very frustrated now cause if this was anyone else I would have just told them to be a guest insteadbandnleave it at that. I don't like checking up on grown people. I feel like I am stuck in a hard position. Dont want to argue with FH over this but also want my deadlines respected so I can move to the next thing...ugghhh.....