According to her, Louis-Philippe was not the son of Philip duke of Orleans, but a suppositious child, his father being one Lorenzo Chiappini, constable at the village of Modigliana in Tuscany. The story is that the duke and duchess of Orleans, travelling under the incognito of Comte and Comtesse de Joinville, were at this village in April 1773, when the duchess gave birth to a daughter; and that the duke, desiring a son in order to prevent the rich Penthièvre inheritance from reverting to his wife's relations in the event of her death, bribed the Chiappinis to substitute their newly-born male child for his own.
Maria Stella, the supposed daughter of Chiappini, went on the stage at Florence, where her putative parents had settled, and there at the age of thirteen became the wife of the first Lord Newborough, after whose death she married the Russian Count Ungern-Sternberg.
On the death of her putative father in 1821 she received a letter, written by him shortly before his death, in which he confessed that she was not his daughter, adding "Heaven has repaired my fault, since you are in a better position than your real father, though he was of almost similar rank" (i.e. a French nobleman). Maria Stella henceforward devoted her time and fortune to establishing her identity.
Her first success was the judgment of the episcopal court at Faenza, which in 1824 declared that the Comte Louis de Joinville exchanged his daughter for the son of Lorenzo Chiappini, and that the Demoiselle de Joinville had been baptized as Maria Stella, with the false statement that she was the daughter of L Chiappini and his wife. The discovery that Joinville was a countship of the Orleans family, and a real or fancied resemblance of Louis Philippe to Chiappini, convinced her that the duke of Orleans was the person for whose sake she had been cheated of her birthright, a conviction strengthened by the striking resemblance which many people discovered in her to the princesses of the Orleans family.
In 1830 she published her proofs under the title Maria Stella ou un éclhange d'une demoiselle du plus haut rang contre in garçon de plus vile condition (reprinted 1839 and 1849). This coincided with the advent of Louis Philippe to the throne, and her claim became a weapon for those who wished to throw discredit and ridicule on the bourgeois monarch. He for his part treated the whole thing with amused contempt, and Baroness Newborough-Sternburg de Joinville, or Marie Etoile d'Orléans, as she called herself, was suffered to live in Paris until on the 23rd of December 1843 she died in poverty and obscurity.
In spite of much discussion and investigation, the case of Maria Stella remains one of the unsolved problems of history. Sir Ralph Payne Gallwey's Mystery of Maria Stella, Lady Newborough (London, 1907), is founded on her own accounts and argues in favour of her point of view.
More convincing, however, is Maurice Vitrac's Philippe-Egalité et M. Chiappini (Paris, 1907), which is based on unpublished material in the Archives nationales. M. Vitrac seeks to overthrow Maria Stella's case by an Alibi. The duke and duchess of Chartres could not have been at Modigliana in April 1773, for the simple reason that they can be proved at that time to have been in Paris. On the 8th of April the duke, according to the official Gazette de France, took part in the Maundy Thursday ceremonies at Versailles; from the 7th to the 14th he was in constant attendance at the lodge of Freemasons of which he had just been elected grand master. Moreover, it was impossible for the first prince of the blood royal to leave France without the royal permission, and his absence would certainly have been remarked. Lastly, the duchess's accouchement, a semi-public function in the case of royal princesses, did not take place till the 6th of October. M. Vitrac identifies the real father of Maria Stella with Count Carlo Battaglini of Rimini, who died in 1796 without issue; the case being not one of substitution, but of ordinary farming out to avoid a scandal.