This was my porcelain doll....
I bought some very fine black ribbon, and tried sewing that on, but it refused to curve and looked even worse, so that got all picked off too. Finally, I drenched the original braid with FrayCheck to help give it some more body, and hopefully keep it the same width throughout. And that worked!
and no amount of corseting is ever going to help, so her jacket just fits 'naturally'.