Need to vent about future sil

Just because she's in your wedding doesn't mean that you get to meddle in her finances. If she needs to work to make money, then she needs to work. It doesn't matter what that money is for. Assuming that everyone's dresses are coming from the same store since you're shopping together, I would think that her dress, from the same store, will be similar quality. If you're not comfortable with her choosing her dress, you can pick 10 or so for her to choose from, but you should also give your other bridesmaids the same supervision.

Similarly to previous comments, I find myself in situations sometimes where I have to remind myself that I can't control how other people spend their time/money, even though it is different than what I would've done with it. It's totally fine to be a little upset, but don't let that sour your appointment with the rest of the girls tomorrow!

This was my SIL to a TEE!!! I think you're spot on with the idea of giving her a few options to choose from instead of a general "match this color swatch in a floor length dress". Sometimes we feel like it should be less stressful when we give options, but give too many options and it almost has the reverse effect! Take pictures/save the dress styles of the dresses chosen by other bridesmaids at the appointment and then take some time to show them to your FSIL and provide options for her (try and do so soon in case she needs to develop a savings plan for the dress). Even better, get her schedule and the two of you can plan a shopping trip for the following weekend so she can feel included (and you don't have to divulge that you don't trust her solo fashion judgement). Try and show your excitement, and if she asks about the speech tell her y'all have decided to limit speeches to MOH and Best Man (or whatever you've decided) but you so appreciate her wanting to be a part of the big day! It's okay to be outwardly appreciative of your FSILs efforts, while also mentally preparing for her to not take on additional responsibilities/be as reliable as some other ladies on the big day Good luck!!