DW_a_mom wrote:
I'm probably too late with this, but ...
My approach has always been to lay it all out realistically, ie explain what it will be like and what your concerns are, why other girls like it, all the while noting the choice is hers and she does not have to do something just because other kids are. Then find out what she thinks and wants, and support it.
And if the only thing really attracting her to it is the pretty dress tell her that she could always choose a night at the Opera (or symphony, or other dress-up event) event, and you would happily buy the dress and make her feel special.
This sounds like a good approach, thank you. She would enjoy this more with no anxiety attached

I won't put it out entirely, just not at this time, is all. She is not in a good place socially right now.