Complex sentence: In 1824 Charles Albert and Maria Theresa were appointed heirs to the throne by Victor Emmanuel I of Sardinia and became King and Queen Consort in 1831, when his successor Charles Felix of Sardinia died without issue.
Split into simpler sentences: In 1824 Charles Albert was recognised as heir to the throne by Victor Emmanuel I of Sardinia. He and Maria Theresa became king and queen in 1831, when his successor Charles Felix of Sardinia died without issue.