That is stunning glad it got done....as for the stain....I watched a program years ago and the lady swore by this......equal parts of biz....ivory dish soap......hot water as hot as possible let soak.......rinse and keep doing this till stain comes out.....she used it on antique wedding dresses
I had something with a water stain similar to what yours looks like and by golly it cleaned it...... Good luck....I see you have many helpful hints and mine is a little late but you never know it might help someone......