Ulmo wrote:

I also checked if Galadriel is mentioned as having a brother. The closest it gets is that Galadriel and Finrod were both of the House of Finarphir [sic].

«Galadriel, greatest of Elven women. She was sister of Finrod Felagund, Friend-of-Men, once king of Nargothrond, who gave his life to save Beren son of Barahir.» App.B