Char of Monaco, in the Charlotte news thread I stated incorrectly that Eloise was seated next to Pierre @ Rose ball. It was in fact her sister, one of her sisters, I'm sure you know all their names. I forgot already which sister.
All I can say is that the sister in question looks exactly like Eloise, could easily pass for her identical twin. I hope that narrows it down.
About the Maillots, thanks for the video clip for Juliette Dol. That shows seems interesting. Her brother Augustin, all I know about him is he used to compete in the jumpings with Charlotte (late 90s, early 2000s) and now studies at Lycee Charlemagne in Paris.