Actually, I've asked this before, but got no answer. I read in the Royal Diaries book about Marie Antoinette that she had to take her Austrian clothes off in front of all those women and get her French clothes. She also had to take her baths in front of other women. I know those diaries aren't very accurate, so what really happened?
I'm sorry, but it's a legend. Yes, it was an old tradition for foreigner princesses who married french princes. They had to leave "even a little ribbon which was not french".
But at Marie-Antoinette's time, it was fallen into inuse.
André Castelot, in his reference biography of the Queen, explains that this story comes from Mme Campan's "Mémoires", who, about this like about other things, made a mistake.
He proves that, when she crossed the anstrian-french border, Marie-Antoinette was dressed with a dress which had been brought from Vienna, and that she conserved with her in France all her austrian "youg lady"'s jewel...
For the bathes, yes, she had to take her bads in front of her chamber maids. But there is a point: she always was wearing a long flannel gown to take these bathes...