I don't think it sounds too old. I knew a girl who went by
Rita. I also love
Margot so I would probably use that as a NN. Not that you asked about NN, but there you go! :)
Marguerite LouisaMarguerite Celine (Frenchy?) /
Selene
For some reason I want to pair it with very soft names like
Marguerite CecileMarguerite FleurMarguerite Saffron (I don't even really like
Saffron as a name but it just sounds really pretty I think)
Marguerite OpheliaMarguerite Helene