“Filles Du Roi” (“Daughters of the King”) is not quite that.
"Daughters of the King" are princesses these “Filles Du Roi” are
very far from that.
"Filles" in French can be "daughters" but it's also "girls"
including young women, and
at that time it would have included ANY unmarried woman (as in "vieille fille")
so “Filles Du Roi” would be s.t. along the lines of "девојке које вам је Краљ дао/послао" absolutly no way that it could mean "Краљеве кћерке" - even as a figure of speech - especially given the mentality of that historical period in France.
https://en.wikipedia.org/wiki/King's_Daughters