Bridesmaid style choosing to stand out

Hi everyone, I'm in serious need of some advice. I have four bridesmaids including my sister who is the MOH. I opted to go for matching colors and different styles as I wanted my BMs to feel comfortable in what they are wearing. I asked that they pick from Azazie, which I loved because you can try on before buying and their prices and reviews are great. However, one of my BMs, FHs sister , kept showing me different dresses that were more along the the line of evening gowns. I don't think she understands what it means to be a bridesmaid and what bridesmaids should wear. She stressed that she would feel comfortable in sleeves and Azazie didn't have the sleeves she wanted. So we moved to Babaroni as it had a long sleeve BMs dress. And then just yesterday, she showed me a long sleeve evening dress from Jjshouse. After I pointed out it was a evening dress, she showed me another dress from JJs that was a BMs dress but was still along the line of an evening dress (see first pic).

I think I shot myself in the foot with this one. My other BMs are not like this and have picked styles that are more along the lines of a traditional BM dress (2nd pic). This BM just has a personal style of elegance and wants to display that. If I allowed them to choose their own styles, shouldn't I be okay with this? I did put my foot down when she asked to wear a metal flower crown. I told her that if she were to wear one, all the girls need to and it would need to compliment what I was wearing. I'm also worried her dress is super elegant and I wasn't going for that with my BMs. I don't know what to do. If I should be okay with how I set my bed and lay in it or sit down with her and have an awkward conversation about how BMs should really not be wearing dresses that don't match the theme, and I had a specific look I was going for. My dress is also romantic and now I'm worried more elegant BMs dresses will make mine look too simple. Omigosh I don't know what to think 😵