It looks as though Susannah decided to use Anna.
1881 census 9 Sydney Street Onchan:
Anna Watts servant Unm b IOM Glen May (that is James & Maria's address in 1881).

Brian has Anna Watts m R H Kneale Jan 24 1885. Also Sarah Kneale b Aug 28 1885 to Robert Henry Kneale and Anna Watts.

Robert Sutch and Anna Kneale are on the same marriage record in Ormskirk Lancashire in the July quarter of 1899. Volume 8b page 1469.
In 1891 Lily 9, is with her widowed grandmother Maria in Patrick on Glen Rushen Road.
Anna's second marriage certificate would indicate if she was widowed.
I did not find a record od Robert Kneale's death.