She was under Blanche in the 1911 census.
This is the Household transcription:

Name Relation Condition/Yrs married Se x Age Birth-Year Occupation Where Born:
WATSON, William Head Married M 45 1866 Farmer Isle of Man Marown
WATSON, Selina Wife (had been married 21 years, 8 children, 7 alive) F 43 1868 Isle of Man Marown
WATSON, Charles Son Single M 20 1891 Farmers Son Working On Farm Isle of Man Marown
WATSON, Elsie Daughter Single F 18 1893 Farmers Daughter Dairy Work Isle of Man Marown
WATSON, Jessie Daughter Single F 15 1896 Isle of Man Marown
WATSON, Ernest Son M 14 1897 School Isle of Man Marown
WATSON, Blanche Daughter F 11 1900 School Isle of Man Marown
WATSON, Ivy Daughter F 8 1903 Isle of Man Marown
QUAYLE, Percy Servant Single M 21 1890 Farm Labourer Isle of Man Michael
CANNAN, William Servant Single M 20 1891 Farm Labourer Isle of Man Michael
------------------------------------------------------------
RG number:RG14; Piece:34720; Reference:
RG14PN34720 RD635 SD1 ED6/3 SN44
Registration District:Isle of Man; Enumeration District:6/3; Parish:Marown.
Address:
Ballafreer Union Mills Marown Isle of Man
[House had 10 rooms, not counting scullery, landing, lobby, closet, bathroom.]
Form filled in and signed by William Watson.

Sue