Working Idea
In OTL Maria bore him twelve children, with her first born, 10 months after the wedding. Let’s say she doesn’t contract gonorrhea.
Rudolf, Crown Prince of Austria (21/8/1858–30/1/1889) m. 10/5/1881, Infanta Maria Antónia of Portugal (28/11/1862–14/5/1959)
Francis Joseph II (B. 25/3/1882, R. 21/11/1916, D. 11/2/1961) m. 1900, Infanta Maria Teresa of Spain (12/11/1882–23/9/1912)
Francis Joseph III of Austria (B. 22/1/1902, R. 11/2/1961, D. 30/5/1991) m. 1920, Princess Mafalda of Italy (2/11/1902-9/5/1989)
Francis Joseph IV (B. 6/8/1926, R. 30/5/1991, D. 23/5/2013) m. 1964
Archduke of Austria (30/10/1927–31/1/1999).
Archduke of Austria (3/6/1937–3/1/1998)
Archduchess Elisabeth Maria (8/10/1940-)
Archduchess Maria Antónia (6/12/1906-14 May 1983) m. 1922, Tsar Alexei II (B. (12/8/1904, R. 4/5/1939, D. 30/7/1969)
Archduchess Maria Theresa (26/3/1909-16/8/1966) m. 1926, Leopold III of Belgium (3/11/1901–25/9/1983)
Archduchess Maria Elizabeth (3/10/1911-11/9/1953)
Archduchess Maria Sophie (15/9/1912-9/5/1918)
Archduchess Elizabeth Adelaide (21/1/1883- m. 1903, Wilhelm III of Germany, (6/5/1882–20/7/1951)
Archduke Karl Joseph of Austria (22/5/1884-
Archduchess Maria Sophie (5/8/1885–6/2/1959) m. 1901, Archduke Franz Ferdinand of Austria (18/12/1863–5/6/1931)
Archduke Michael Francis of Austria (1/8/1886–14/3/1934)
Archduke Ferdinand the Posthumous, later Grand Duke and Regent of Luxembourg (25/4/1889–7/5/1977) m. 1913, Marie-Adélaïde, Grand Duchess of Luxembourg (14/6/1894–24/1/1924)
William V, Grand Duke of Luxembourg