Hi,
I've just done a search on Ancestry for Agnes/Agnus Donaghay which came back with 7 results. After looking through them all none of them show her living with children with the surname Turner.
The most promising entry was from 1930 details below where I have agnes living with a stepfather who's surname is Wallace. None of the other search results show a wallace.
Residence : Pawtucket, Providence, Rhode Island
Joseph Wallace / Head / Age 33 / Birth year 1897 / Birth Place Scotland / Married
Agnes Wallace / Wife / Age 36 / Birth year 1894 / Birth Place Scotland / Married
Martha Wallace / Daughter / Age 1 / Birth year 1928 / Birth Place Rhode Island / Single
Latitia Wallace / Daughter / Age 0 / Birth year 1930 / Birth Place Rhode Island / Single
James Donaghey / Stepson / Age 18 / Birth year 1912 / Birth Place Rhode Island / Single
Agnes Donaghey / Stepdaughter / Age 17 / Birth year 1913 / Birth Place Rhode Island / Single
Helen Donaghey / Stepdaughter / Age 12 / Birth year 1918 / Birth Place Rhode Island / Single
Janet Park / Mother in Law / Age 65 / Birth year 1865 / Birth Place Scotland / Widowed
if this is the correct record then I have also found the family in the 1920 census and Agnes (the younger) is living with her widowed mother, brother (James) , sister (Ellen) and grandmother (Janet park) in Pawtucket, Providence, Rhode Island.
If this isn't the correct record then it would help to know where in the US they were living so I could search on a specific state.
Michelle