Margaret Connor/Connors/O'Connor

In 1855 great great grandfather, a convict, was given permission to marry a free woman by the name of Margaret Connors. It appear they did not marry but did have a number of children together. The only information we have about her is that she was 23 when she 'married' and that she was from County Clare (death certificate) This means she had to arrive in about 1851. A search of the Tasmanian records failed to find anyone by that name arriving in 1850-52.  A search of the passenger lists of the Beulah and Calcutta carring girls from  Clare workhouses have a Margaret O'Connor (Ennistymon) on th Beulah and Margaret Connor (Scarriff) on the Calcutta.Is there any way to identify either of these girls in a family group?