Complex sentence: Anna Miełżyńska (1600-1640) was the grandmother of Catherine Opalinska, the Queen Consort of King Stanislaus Leszczynski of Poland and the great-grandmother of Maria Leszczynska, the queen consort of Louis XV of France.
Split into simpler sentences: Anna Miełżyńska (1600-1640) was the grandmother of Catherine Opalinska, the queen consort of King Stanislaus Leszczynski of Poland. She was also the great-grandmother of Maria Leszczynska, the queen consort of Louis XV of France.