Think I have found her in the 1901 census as below.
Aletha Knapper abt 1882Yorkshire, England DaughterNewchapelStaffordshire
Elizabeth A Knapper abt 1852Galley Bank, Staffordshire, England WifeNewchapelStaffordshire
Joseph Knapper abt 1848Kidsgrove, Staffordshire, England HeadNewchapelStaffordshire
Joseph Knapper abt 1888Normanton, Yorkshire, England SonNewchapelStaffordshire