Most probably the biological daughter of Richard Wagner and Cosima von Bülow (Liszt)

Baron Hans Guido von Bülow

Bülow was perhaps the most prominent of the early students of Hungarian virtuoso pianist, conductor and composer Franz Liszt. He became acquainted with and eventually married Liszt's daughter Cosima, who later left him for Wagner.

In 1851 he became a student of Liszt, marrying Liszt's daughter Cosima in 1857. They had two daughters: Daniela, born in 1860 and Blandine, born in 1863.

However, his wife Cosima, who had been carrying on an extramarital affair with Richard Wagner for some time, left him in 1868, taking with her two of their four daughters, Isolde and Eva—the two whom Richard Wagner had fathered — and in 1870 divorced Bülow.