Also I'm really sorry about my grammar in the last post.
Thank you for all of your suggestions. I'm trying to keep her in but it kinda doesn't seem possible at this moment.
I have given her the opportunity to make her own decisions. I have a group chat with all of my bridemaids in I sent out a general text letting everyone know that it's ok for them to back down. She didn't take the hint instead she started to call her about puppies. (Her dog had puppies) I've shown her different dresses, I've recommended that she doesn't have to get everything professionally done. I've also explained to her about the flowers and the original price and agreement. (Flowers: bridemaids only have to pay $10! The original price was $50. Second mother is paying for some and also helping the florist. I'm also helping with the materials. Sil is refusing to pay the $10. I've kinda had to give her an option of paying the $10 or the $50. She has blocked me on phone and on social media. I'm kinda at a I don't know what to do at this point. Now my future husband has spoke to his sister about the matter. She hasn't ready the message yet. So we'll see how it goes. Fingers crossed that everything goes well.
For the driving commitment she has found a ride but she has told me that she'll be at the church when she can get there. So that's not really going well at the moment. I'm trying to work with her I'm making suggestions and offering things but it's not helping.