Re Creers - for anyone who might be interested the Creer family group on the Cassandra 1827 were:-
Hannah Creer nee Sayle - her husband was James Creer (m Braddan Jan 19 1817)
Their children were William, Mary Ann (not Margaret!), James and Charlotte. Presumably William Sail (sic) was her father and Eliza her mother(?). There is no trace of James Creer dying around 1826 but he must have disappeared from the scene someway or had already gone ahead to the USA.

cheers