Here is a short bio on Erzsi:
Born on September 2nd 1883, she was the only child of Crown Prince Rudolf of Austria and Princess Stephanie of Belgium. When her father died in January 1889, her grandfather, Emperor Franz Joseph, took over the guardianship of his much beloved granddaughter. At a young age she displayed a strong personality, even stubbornness, as well as an opposition against the court in Vienna.
She was cold and distant towards her mother, especially after she married Count Elemer Lonyay in 1900. On January 23rd 1902 in Vienna, 'Erzsi' married Prince Otto zu Windisch-Graetz, a marriage not befitting her social standing. However, Emperor Franz Joseph very generously assured that she could live in luxury with her husband.
Between 1904 and 1909 four children were born, but the marriage became a very unhappy one. Both Erzsi and Otto flaunted their much-discussed affaires. Only after the death of her grandfather, and the end of the monarchy, was Elisabeth able to obtain a divorce. However, the legal process, started in 1919, was finalized only in 1924 and then a yearlong fight started about the custody of their children. These were kidnapped with police action causing Elisabeth to seek help from the social democrats.
At this time she started to live with the social democratic teacher and politician, Leopold Petzneck, and remained at his side when there were marches and meetings where she was accepted with great respect. In February 1934 Petzneck was arrested and jailed by the Austrian government and, in 1944, sent to the concentration camp in Dachau. Surviving this ordeal, they married on 4 May 1948 in Vienna. In 1956 Leopold Petzneck died and Elisabeth became a reclusive. She suffered from gout and most of the time was wheelchair bound. In her will she left her inheritance to the 'Wiener Gemeinde'.
I had an impression, that she wasn't good mother. When I look at the photos taken with her children she seams very cold and distant to me.