Hi again, I think the Sarah Stranger in 1841 with William & family is Sally in 1851:-
Sally Stranger 39 Widow
Mary Ann 11
Sarah 6
All born Helston
Residing North Street, Madron, Penzance
Census ref HO107/1918/685/17
Sarah Stranger b c 1844 is a Servant b Helston in 1861
Keyboard86