Eu

The comtesse d'Eu, Isabel (1846–1921), daughter of Emperor Pedro II of Brazil and heiress to the Brazilian throne, wife since 1864 of Gaston d'Orléans, comte d'Eu, grandson of King Louis-Philippe (en.wikipedia «Isabel, Princess Imperial of Brazil»). Marie mentions her once, on 1881-03-25 (091.0355), in the evening at the Gavinis': the marquis de Graves «qui était dans la loge du duc de Nemours et de la comtesse d'Eu, future impératrice»; a footnote explains that Nemours was the father of the comte d'Eu. Mon Journal indexes: «Eu (comte d'), 33» and «Eu (comtesse), 33» (t.12), «Eu (comtesse de), 104» (t.14). The tag is a title, not a name; a fuller entry could be filed under Isabel's name.