 In 1826 , shortly after the death of his father , Meyerbeer married his cousin , <unk> <unk> ( 1804 – 1886 ) . The marriage which may have been ' dynastic ' in its origins proved to be stable and devoted ; the couple were to have five children , of whom the three youngest ( all daughters ) survived to adulthood . In the same year , following the death of Carl Maria von Weber , Weber 's widow asked Meyerbeer to complete her husband 's unfinished comic opera Die <unk> <unk> . This was to cause him much trouble over future years , as he found the material insufficient to work on . Eventually in 1852 he settled the matter with Weber 's heirs by handing them Weber 's drafts and a cash compensation . ( The opera was later completed by Gustav Mahler ) . 
